Inventors list

Assignees list

Classification tree browser

Top 100 Inventors

Top 100 Assignees


Including Class D amplifier

Subclass of:

330 - Amplifiers

330250000 - WITH SEMICONDUCTOR AMPLIFYING DEVICE (E.G., TRANSISTOR)

Patent class list (only not empty are listed)

Deeper subclasses:

Entries
DocumentTitleDate
20090160553DISTORTION SUPPRESSION CIRCUIT FOR DIGITAL CLASS-D AUDIO AMPLIFIER - A digital Class-D amplifier distortion suppression circuit design is disclosed. A distortion suppression feedback loop is described to improve audio performance by suppressing output stage non-linearity and improving power supply noise rejection achieving reduced THD+N. The feedback loop is placed around the power stage. It forces tracking between the audio band signals at the input and output of the power stage by automatically adjusting the gating signal timing based on sensed effective duty ratio error. Error sensing and compensation are performed using techniques that lend to simple circuit implementation.06-25-2009
20090027120CLASS-D AMPLIFIER WITH NOISE-IMMUNITY FEEDBACK - A class-D amplifier includes a switching transistor section, a filter, an analog to digital converter, and a feedback module. The switching transistor section is operably coupled to convert a serial input into a switched output signal. The filter is operably coupled to filter the switched output signal to produce an output of the class-D amplifier. The analog to digital converter is operably coupled to convert an analog input into a multi-bit digital signal based on a feedback signal, wherein the serial input corresponds to the multi-bit digital signal. The feedback module is operably coupled to the produce the feedback signal based on at least one varying property of the switching transistor section.01-29-2009
20100019847AMPLIFIER EMPLOYING INTERLEAVED SIGNALS FOR PWM RIPPLE SUPPRESSION - An amplifier having improved distortion characteristics is set forth. The amplifier includes an interleaved PWM amplifier that generates interleaved PWM pulses in response to a modified input signal and one or more carrier signals. The interleaved PWM pulses of the amplifier are used to drive a power stage, such as an opposed current power stage. The amplifier also includes an interleaved PWM generator that provides interleaved PWM pulses in response to the modified input signal and one or more further carrier signals. The carrier signals used by the PWM generator may differ in phase from the carrier signals used by the interleaved PWM amplifier to generate its interleaved PWM pulses. One or more feedback circuits are employed in the generation of the modified input signal. More particularly, the feedback circuit(s) generates the modified input signal based on an input signal that is to be amplified and the interleaved PWM pulses of the interleaved PWM generator.01-28-2010
20080258811DISTRIBUTED CLASS G TYPE AMPLIFIER SWITCHING METHOD - An improved Class G type amplifier is provided which switches between multiple power rails depending upon the instantaneous amplitude of the input signal versus the power rails without excessive distortion. The low voltage (inner) amplifier includes a plurality of parallel amplifier devices, and the high voltage (outer) amplifier includes a plurality of parallel amplifier devices. A plurality of switches each couples the input signal to either a respective one of the inner amplifier devices or a respective one of the outer amplifier devices. The switches are activated sequentially, such that the switching from inner amplifier devices to outer amplifier devices or vice versa is staggered over time. This avoids having a single, large glitch in the output and spreads multiple smaller glitches over enough time so that some of the radiated glitch energy can fall within frequencies where amplifier feedback circuitry can eliminate its noise. The switches are sequentially activated by a series of delay elements.10-23-2008
20100117731Thermal regulation of a class-D audio amplifier - A class-D audio amplifier is protected by thermal regulation which decreases the gain of the class-D audio amplifier by asserting an over-temperature signal when the temperature of the class-D audio amplifier is detected to be higher than a threshold. The output of the class-D audio amplifier is therefore reduced by the smaller gain, and the chance for the class-D audio amplifier to stop working due to overheating is greatly reduced.05-13-2010
20080297248CLASS D AMPLIFIER CIRCUIT WITH BI-DIRECTIONAL POWER SWITCH - A Class D amplifier circuit in accordance with an embodiment of the present application includes a converter stage operable to provide a desired AC voltage and a Class D amplifier stage, connected to the converter stage. The Class D amplifier stage includes a first bi-directional switch connected to the converter stage, a second bi-directional switch, connected in series with the first bi-directional switch, wherein the first and second bi-directional switches are connected across the desired AC voltage provided by the converter stage and a controller operable to turn the first and second bi-directional switches ON and OFF such that a desired voltage is provided at a midpoint node positioned between the first bi-directional switch and the second bi-directional switch.12-04-2008
20130033319AMPLIFIER CIRCUITS AND MODULATION SIGNAL GENERATING CIRCUITS THEREIN - An amplifier circuit includes a modulation signal generating circuit, a driving stage circuit and an output stage circuit. The modulation signal generating circuit generates a pair of modulation signals according to a pair of differential input signals and a pair of clock signals. The pair of clock signals includes a first clock signal and a second clock signal having a phase difference therebetween. The driving stage circuit generates a pair of driving signals according to the pair of modulation signals. The output stage circuit generates a pair of amplified output signals according to the pair of driving signals.02-07-2013
20130033318SWITCHING AMPLIFIER AND AUDIO DEVICE - A switching amplifier is provided. The switching amplifier includes an input unit which receives an audio signal; a first switching device and a second switching device which switch and output the audio signal; a first snubber circuit which is commonly connected to the first and second switching devices and which reduces overshoot of the audio signal that is output by the first and second switching devices via switching; and a second snubber circuit which is commonly connected to the first and second switching devices, which is connected in parallel to the first snubber circuit and which reduces the overshoot of the audio signal, wherein the first and second snubber circuits alternately reduce the overshoot of the audio signal.02-07-2013
20100045377Switching Amplifier - A switching amplifier includes a modulator, which includes a pulse generator. The pulse generator generates positive and negative pulses, in response to an input signal, and the frequency of the negative pulses can be controlled independently of the frequency of the positive pulses. The positive pulses and negative pulses are combined to form a composite pulse stream, which can be low-pass filtered such that the filter output is an amplified version of the input signal.02-25-2010
20090243722Reduction of power consumption and EMI of a switching amplifier - A switching amplifier has a network including current sources and resistors connected to the two output terminals of the H-bridge of the switching amplifier, to provide a small current to the load connected between the two output terminals at zero input, whereby the common mode voltage bouncing is reduced and the switching amplifier has less power consumption and reduced electro-magnetic interference.10-01-2009
20130038391METHOD AND APPARATUS FOR REDUCING DISTORTION IN CLASS D AMPLIFIER - Provided are apparatuses and methods for reducing nonlinear distortions in Class D amplifiers by dynamically changing first and second threshold voltages in a pulse width modulator. A Class D amplifier apparatus is disclosed, comprising a pulse width modulator whose operation relies on a first and second threshold value, and a threshold controller which varies the thresholds in response to internal signals in the amplifier. Further, a method of processing Class D amplifier internal signals is disclosed, comprising steps involving measuring internal signals in a Class D amplifier and varying threshold signals in response to those measurements within the amplifier.02-14-2013
20130038392POWER SUPPLY METHOD AND APPARATUS - A method and apparatus for providing a power supply for an amplifier is provided. The power conversion is achieved using synchronous rectifiers in a regulated half bridge power supply, taking the sum of the positive and negative rails as feedback, in order facilitate energy transfer between positive and negative output rails. This minimizes the effects of off side charging and rail sag, as well as achieving good line regulation, while allowing use of very small, low value output capacitors.02-14-2013
20090160551Switching Amplifier - A switching amplifier includes an input end for receiving an input signal, a reference signal reception end for receiving a reference signal, a feedback end for receiving a feedback signal, an output end for outputting an output signal, an integration circuit for performing integration operation on the input signal according to the output signal and the feedback signal, so as to generate an integration result, a comparison circuit coupled to the integration circuit, the reference signal end, and the output end, for comparing the integration result and the reference signal, so as to generate the output signal for the output end, and a feedback circuit coupled between an output end of the integration circuit and the feedback end, for generating the feedback signal for the feedback end to clamp the integration result to a predetermined value when the integration result reaches the predetermined value.06-25-2009
20100109773Class-D Amplifier - A class-D power amplifier according to the present invention includes: a pulse width modulation circuit which modulates an analog signal into low-level and high-level binary signals; and a detection circuit which turns off operation of a circuit connected with a back stage of the pulse modulation circuit if the high level or the low level of the binary signal output from the pulse width modulation circuit is maintained for a predetermined time.05-06-2010
20100109772SIGMA DELTA CLASS D POWER AMPLIFIER AND METHOD THEREOF - A sigma delta class D power amplifier includes a loop filter, a quantizer, and an output stage. The quantizer is coupled to the loop filter and quantifies an error signal according to levels of two reference signals to output a pair of mean signals, wherein different logic combinations of the mean signals belong to one of three quantum states. The output stage is coupled to the quantizer and outputs a corresponding output signal according to the different quantum states to drive a load, wherein a driving current of the output signal belongs to one of the three driving states which include at least a steady state with no current of a power amplifier.05-06-2010
20090153243CLASS D AMPLIFIER - A single-end-output class D amplifier is provided that handles a load such as stereo headphones without using an expensive part such as a crystal resonator or transformer. Class D amplifier 06-18-2009
20100066447FILTER COMPENSATION FOR SWITCHING AMPLIFIERS - Embodiments of the present invention provide methods and systems for limiting bipolar current flow in a switching amplifier. Embodiments of the present invention are directed to a multi-referenced switching amplifier. In some embodiment, the switching amplifier is a dual referenced switching amplifier comprising a regulator between the two references, where the first reference provides coarse modulation to a load and the second reference provides fine modulation to the load. The dual referenced switching amplifiers comprise the output filters made up of an inductor and a capacitor. In some embodiments, fine modulation is not applied to the load, thus limiting bipolar current flow induced by the filter inductors.03-18-2010
20090045873CLOSE-LOOP CLASS-D AUDIO AMPLIFIER AND CONTROL METHOD THEREOF - The present invention discloses a Class-D power amplifier and control method thereof. In one embodiment, the amplifier feeds back the signal at the output node to the inverting input of the comparator, and provides a high frequency triangular wave signal to the non-inverting input of the comparator. In addition, the non-inverting input of the comparator may be coupled to an offset voltage, while the inverting input of the comparator may be coupled to a fixed-frequency rectangular wave signal, a feedback signal which is derived from the output stage and an input signal. In use, the switching frequency may be at least substantially fixed, so as to reduce the influence on the system caused by electromagnetic interruption (EMI). Further, the control circuit is simple, and some devices can be integrated.02-19-2009
20130049862SWITCHING CIRCUIT AND ENVELOPE SIGNAL AMPLIFIER - A switching circuit according to one embodiment has: N switching elements; a connection circuit including N−1 first inductance elements that are connected in series; a second inductance element; and N third inductance elements. Control terminals of the N switching elements are connected to ends of the connection circuit and connection contacts, respectively. One end of the second inductance element is connected to a power supply. The N third inductance elements electrically connects one ends of the N switching elements and the other end of the second inductance element with each other, respectively.02-28-2013
20100001796Radio Frequency (RF) Envelope Pulsing Using Phase Switching of Switch-Mode Power Amplifiers - A radio frequency (RF) power generator includes a first switch-mode amplifier that generates a first RF signal in accordance with a first control signal and a second switch-mode amplifier that generates a second RF signal in accordance with a second control signal. The first and second control signals determine a phase difference between the first and second RF signals. An output signal envelope is based on the first and second RF signals and the phase difference. The first control and second control signals alternate phases of the first and second RF signals.01-07-2010
20130088297PWM Re-Clocking Scheme To Reject Accumulated Asynchronous Jitter - An amplifier may use pulse-width modulators controlling respective sets of switches to produce an amplified version of a source signal. A phase locked loop in the amplifier may generate a differential clock signal. A first processing element operating according to a first supply voltage may generate a PWM signal representative of the source signal, and also generate a clock enable signal corresponding to the differential clock signal. A second processing element (PE2) may receive the differential clock signal, the PWM signal, and the clock enable signal, and level shift the PWM signal and the clock enable signal to operate according to a second supply voltage, and may generate a resampling clock signal from the differential clock signal according to the level shifted clock enable signal. The PE2 may provide a PWM output signal representative of the source signal by resampling the level shifted PWM signal with the resampling clock signal.04-11-2013
20130088296Attenuating Noise and Cross-Talk in an Audio System by Offsetting Outputs In Phase - An amplifier may include two or more pulse-width modulators (PWMs) controlling respective sets of switches to produce an amplified version of a source signal. The clocking for the amplifier may be controlled to delay signal processing within the PWMs relative to one another in time, thereby providing an effective time offset between the respective edge transitions of the controlling signals provided to the respective sets of switches. The PWMs may count down to zero from the next PWM duty-cycle value when a new data sample is detected, beginning a new count for each new sample, with the PWM outputting a pulse when the counter value is nonzero. A “data-sample-ready” signal may be decoded from a master counter, which may be clocked based on the high speed PWM clock, and the decode value may be adjusted to determine when the PWM should initialize to the next data sample.04-11-2013
20090302943CLASS D AMPLIFIER - A class D amplifier including a PWM circuit, a buffer amplifying circuit, a low-pass filter, and two current sources is provided. The PWM circuit transfers an analog signal into a PWM signal. The buffer amplifying circuit amplifies the PMW signal and generates an amplified signal. The low-pass filter will filter high frequency components out from the amplified signal and then transmit the filtered signal to a loading of the class D amplifier. The two current sources provide currents flowing into and out from a feedback node in the PWM circuit, respectively. The charging and discharging provided by the two current sources can generate a triangular signal for the PWM circuit.12-10-2009
20090302942D-CLASS AMPLIFIER - A D-class amplifier that can suppress noise generated when a D-class amplification operation is started/stopped. When a D-class amplification operation is started/stopped, the pulse widths and pulse interval of output signals Pout12-10-2009
20110012677CURRENT SENSING - A switching amplifier comprising: an output driving circuit (01-20-2011
20130063209SWITCHING AMPLIFIER WITH AN INDUCTOR - A switching amplifying method or a switching amplifier for obtaining a linearly amplified replica of an input signal, is highly efficient, and does not have the disadvantage of “dead time” problem related to the class D amplifiers. Another aspect of the present invention provides a switching amplifier that is completely off when there is no input signal. Yet another aspect of the present invention further comprises an act of comparing an input signal with an output feedback signal for detection and correction of overall system signal processes therefore does not require a power supply regulator and is substantially immune to power supply and load perturbations.03-14-2013
20090237159OUTPUT STAGE CIRCUIT - A PWM signal drives a pair of output transistors connected in series between a supply line and ground so that a push-pull current is output toward a speaker via a coil from a point connecting both output transistors. A current limiting resistor has one end connected to the supply line and between the other end and ground is provided a control transistor. Furthermore, a comparator compares the supply line voltage and a reference voltage and turns on the control transistor when the supply line voltage is higher than the reference voltage in the comparison result thereof.09-24-2009
20090237160Switch Mode Power Amplifier Using MIS-HEMT with Field Plate Extension - Disclosed are a switch mode power amplifier and a field effect transistor especially suitable for use in a switch mode power amplifier. The transistor is preferably a compound high electron mobility transistor (HEMT) having a source terminal and a drain terminal with a gate terminal therebetween and positioned on a dielectric material. A field plate extends from the gate terminal over at least two layers of dielectric material towards the drain. The dielectric layers preferably comprise silicon oxide and silicon nitride. A third layer of silicon oxide can be provided with the layer of silicon nitride being positioned between layers of silicon oxide. Etch selectivity is utilized in etching recesses for the gate terminal.09-24-2009
20090033419CLASS D AMPLIFIER WITH INCREASED EFFICIENCY - The present invention is a method of operating a speaker by converting an audio signal to a pulse-width modulated signal that has a plurality of positive pulses and a plurality of negative pulses as a function of the audio signal, then driving an H-bridge circuit interconnected to a speaker, wherein the H-bridge circuit comprises an A-side and a B-side, wherein the A-side comprises a first switching transistor and a second switching transistor, and wherein the B-side comprises a first switching transistor and a second switching transistor. For each positive pulse, the A-side of the H-bridge circuit is driven by pushing the first switching transistor of the A-side while grounding the second switching transistor of the A-side. For each negative pulse, the B-side of the H-bridge circuit is driven by pushing the first switching transistor of the B-side while grounding the second switching transistor of the B-side.02-05-2009
20120229212AMPLIFIER USING MASTER-SLAVE CONTROL SCHEME - Techniques are disclosed relating to charging and discharging gates of transistors. In one embodiment, an apparatus includes first and second drivers. The first driver is configured to discharge a gate of a first transistor, and to send a charge indication to the second driver in response to reaching a Miller plateau for the first transistor. The second driver is configured to charge a gate of a second transistor above a threshold voltage in response to receiving the charge indication. In some embodiments, the second driver is configured to begin charging the gate of the second transistor to a voltage below the threshold voltage when the first driver begins discharging the gate of the first transistor begins, and to wait to charge the gate of the second transistor above the threshold voltage until the charge indication has been received.09-13-2012
20120235743APPARATUS FOR OUTPUTTING SYMMETRICAL SIGNAL AND AMPLIFIER CIRCUIT - A symmetrical signal generator that includes a first signal part configured to produce a first output pulse signal using a first input pulse signal and a second input pulse signal asymmetrical to each other, and a second signal part configured to produce a second output pulse signal using the first input pulse signal and the second input pulse signal. The second output pulse signal is one inverted to be symmetrical to the first output pulse signal.09-20-2012
20130162351POWER AMPLIFIER AND LIQUID JET PRINTING APPARATUS - A power amplifier includes: a modulator pulse-modulating a drive waveform signal serving as a reference of a drive signal applied to an actuator and outputting a plurality of modulated signals; a digital power amplifier having a plurality of digital power amplifier stages each including a pair of push-pull switching elements, amplifying the power of the plurality of modulated signals, and outputting multi-value amplified digital signals; and a low pass filter smoothing the amplified digital signals and outputting the drive signal, wherein the modulator includes a control section switching one of a state where the same modulated signal is connected to two or more of the digital power amplifier stages and a state where different modulated signals are connected to different digital power amplifier stages to the other.06-27-2013
20110068869SINGLE-ENDED CLASS-D AMPLIFIER WITH DUAL FEEDBACK LOOP SCHEME - A single-ended class-D amplifier with dual feedback loop scheme has a gain adjusting circuit, a second-order integrator, two comparators, a logic circuit, an output driver and an inverter. The output driver cooperates with the inverter to produce a differential signal. The differential signal is input to the second-order integrator to construct a dual feedback differential loop to eliminate noise of output signals of the class-D amplifier, and offer enhanced signal to noise and distortion ratio (SNDR).03-24-2011
20080309406Full-Bridge Class-D Power Amplifier - The present invention relates to a full bridge class-D amplifier where one of the output terminals (12-18-2008
20100045376CLASS D AMPLIFIER CONTROL CIRCUIT AND METHOD - Circuit and method for a Class D amplifier. In one exemplary embodiment, an audio amplifier is disclosed. A closed loop configuration for driving high and low side driver transistors is provided, each circuit is compatible with advanced sub micron semiconductor processes. The analog time varying input is coupled to one input of a sigma delta analog to digital converter. A feedback signal from the output is also input to the analog to digital converter. A bit stream is output by the analog to digital converter. A decimator receives this bit stream and downconverts the samples to digital values at a lower frequency. A digital filter with adaptable coefficients is used to filter that signal and a digital pulse width modulator then develops an analog differential PWM signal. A predriver inputs the PWM signal and derives the output gating signals to control the high and low side drivers of a Class D amplifier.02-25-2010
20110285463OUTPUT CIRCUITS WITH CLASS D AMPLIFIER - Output circuits using pulse width modulation (PWM) and/or pulse density modulation (PDM) are described. In one aspect, a PWM output circuit includes a PWM modulator that operates based on a square wave signal instead of a sawtooth or triangular wave signal. In another aspect, a PDM output circuit includes a PDM modulator that uses variable reference voltages to reduce variations in switching frequency. In yet another aspect, a dual-mode output circuit supports both PWM and PDM and includes a pulse modulator and a class D amplifier. The pulse modulator performs PWM on an input signal if a PWM mode is selected and performs PDM on the input signal if a PDM mode is selected. The class D amplifier receives a driver signal from the pulse modulator and generates an output signal.11-24-2011
20090219090OUTPUT DC OFFSET PROTECTION FOR CLASS D AMPLIFIERS - A class D amplifier with output DC offset protection is disclosed. The DC offset protection receives a PWM input signals from the outputs and investigates the PWM output signals whether there is a large DC voltage difference is being reflected on the speaker load. If so, shutdown signal SD will be sent by the DC offset protection to the PWM control logic and gate driver, thus, shutting down the output of the class D system and preventing disastrous condition from being develop across the speaker.09-03-2009
20080315948Circuit architecture having differential processing for use in half bridges and full bridges and methods therefore - Circuit architecture is disclosed that includes one or more half bridges, the one or more half bridges including signal processing circuitry including first and second inputs and one or more outputs. The circuit architecture also includes a driver stage coupled to the one or more outputs of the signal processing circuitry and configured to create at least one output, one of the at least one outputs suitable to couple to a load. The circuit architecture further includes a first feedback loop coupling the at least one output of the driver stage to a first input of the signal processing stage, and includes a second feedback loop coupling the at least one output of the driver stage to a second input of the signal processing stage, where signals on the first and second feedback loops have inverted polarity. Methods and computer-readable media are also disclosed.12-25-2008
20080265989Filterless class-D speaker driver with less switching - Methods for designing a filterless class-D amplifier and driver are described herein. In the exemplary embodiment, a feedback loop is used to stabilize the filterless class-D amplifier. A pulse width modulated (PWM) output signal is generated by adding a comparator input signal to a comparative signal, and comparing the sum to a peak voltage, which can be a peak value of the comparative signal. A limit of one PWM sample will be generated half per period of the comparative signal, resulting in lower dynamic switching noise and a decreased sensitivity to jitter noise than conventional filterless class-D amplifiers.10-30-2008
20100264985CLOSE-LOOP CLASS-D AUDIO AMPLIFIER AND CONTROL METHOD THEREOF - The present invention discloses a Class-D power amplifier and control method thereof. In one embodiment, the amplifier feeds back the signal at the output node to the inverting input of the comparator, and provides a high frequency triangular wave signal to the non-inverting input of the comparator. In addition, the non-inverting input of the comparator may be coupled to an offset voltage, while the inverting input of the comparator may be coupled to a fixed-frequency rectangular wave signal, a feedback signal which is derived from the output stage and an input signal. In use, the switching frequency may be at least substantially fixed, so as to reduce the influence on the system caused by electromagnetic interruption (EMI). Further, the control circuit is simple, and some devices can be integrated.10-21-2010
20110063027Class-D amplifier - A class-D amplifier for generating from an input signal a digital signal for driving a load, includes an output limit instruction generating section that detects that the digital signal falls outside a limit range and that outputs an output limit instruction signal, an attenuation instruction pulse generating section that includes an integrator for integrating the output limit instruction signal and that outputs a periodical attenuation instruction pulse having pulse width corresponding to an integrated value in the integrator, an attenuating section provided in an input path for the input signal and that attenuates the input signal based on the attenuation instruction pulse, and a mute control section that controls the integrated value in the integrator independently of the output limit instruction signal to control an amount of the attenuation of the attenuating section applied to the input signal.03-17-2011
20100117732POWER AMPLIFIER AND LIQUID JET PRINTING APPARATUS - A power amplifier includes: a modulator pulse-modulating a drive waveform signal serving as a reference of a drive signal applied to actuators and outputting a modulated signal; a digital power amplifier amplifying the power of the modulated signal and outputting an amplified digital signal; a low pass filter smoothing the amplified digital signal and outputting the drive signal; and an inverse filter circuit being disposed at a front stage of the modulator and capable of obtaining a desired waveform precision of the drive signal even when a frequency characteristic of a filter including the low pass filter and an electrostatic capacitor of the actuators varies depending on the number of driven actuators, wherein the inverse filter circuits include a plurality of inverse filters connected in series.05-13-2010
20100117730D/A converter circuit and digital input class-D amplifier - The present invention provides a D/A converter circuit which enables D/A conversion with a high precision and can prevent occurrence of a limit cycle component in the case where an input signal is low, and can also prevent the effect of dither signal from occurring in an analog signal which is a D/A conversion result.05-13-2010
20100085118Dead-time locking circuit - The dead-time locking circuit includes phase detector and a delay-comparator. The delay-comparator includes two input ends for receiving phase adjusting signal and the input-exchanging signal received by the class D amplifier. After comparing, the delay-comparator outputs a gate driving signal. The phase detector detects the phase difference between the output signal of the class D amplifier and the gate driving signal of the power transistor of the class D amplifier, and accordingly adjusts the rising/falling edges of the gate driving signal outputted from and the comparator via the charge-pump. In this way, the dead-time can be locked at the predetermined value.04-08-2010
20100079207STAGED LINEAR CONVERSION METHOD - The present invention discloses a staged linear conversion method, which comprises steps: receiving a staged linear triangular-wave signal and a reference signal with a comparator, wherein the staged linear triangular-wave signal has a waveform having at least three different slopes; and performing a conversion on the reference signal to output a PWM signal according to the voltages of the intersections of the staged linear triangular-wave signal and the reference signal and the slope variation of the staged linear triangular-wave signal. The present invention can reduce the distortion of saturation signals when a Class D amplifier performs signal conversion.04-01-2010
20100079208Minimum pulse generation in a class-D amplifier - For minimum pulse generation in a class-D amplifier, a trapezoid switching waveform shape is used to replace the tradition triangle type to generate PWM pulses. Two voltages are compared with a sawtooth wave signal to generate the trapezoid waveform signal and a constant pulse width signal. An audio input signal is compared with the trapezoid waveform signal to generate a pulse width modulation signal, and either the pulse width modulation signal or the constant pulse width signal is used for driving a load at an output of the class-D amplifier. Flexible minimum pulse width could be obtained by offsetting one of the two voltages in generation of the constant pulse width signal.04-01-2010
20100090764CLASS D AMPLIFIER - The invention refers to an amplifier (04-15-2010
20080211578Delta Sigma-Type AD converter, class-D amplifier, and DC-DC converter - A ΔΣ-type AD converter includes a subtractor which receives an analogue input signal and a feedback signal and which outputs a signal pertaining to a difference between the signals, an integrator which integrates a signal output from the subtractor, a comparator which binarizes a signal output from the integrator by comparing with a predetermined threshold value, a counter which measures respective pulse widths of a signal output from the comparator, and a PWM circuit which outputs a pulse signal of a predetermined period having a duty cycle responsive to a count value output from the counter and which feeds back the pulse signal as the feedback signal to the subtractor. The counter measures the respective pulse widths in each PWM frame period in synchronism with the PWM circuit, and the PWM circuit feeds back to the subtractor a pulse signal whose duty cycle is set in accordance with a value of the measured pulse width in a next PWM frame. A count value output from the counter is extracted as a converted digital output value.09-04-2008
20080211577AUDIO POWER AMPLIFIER USING VIRTUAL GROUND AND METHOD OF PROCESSING SIGNAL IN THE AUDIO POWER AMPLIFIER - An audio power amplifier provides a virtual ground to reduce power on/off noise and a method for processing a signal in the audio power amplifier. The audio power amplifier includes a switching amplifier to amplify a small output pulse width modulation (PWM) signal so as to generate a large output PWM signal, a pulse generating unit to generate a pulse signal having the same level as that of the PWM signal level, a first low pass filter to allow the large output PWM signal amplified by the switching amplifier to be low-pass filtered so as to restore the PWM signal to an audio signal, and a second low pass filter to allow the pulse signal generated by the pulse signal generating unit to be low-pass filtered so as to convert the pulse signal into a virtual ground voltage with respect to the restored audio signal.09-04-2008
20090115514Class D amplifier - A class D amplifier includes: an amplifier that generates a digital signal for driving a load based on an input signal; an attenuator that attenuates the input signal according to an attenuation command signal; and a clip prevention controller that outputs the attenuation command signal to intermittently attenuate the input signal when the digital signal is brought into a clip state or a near-clip state.05-07-2009
20090261902Asynchronous Error Correction Circuit for Switching Amplifier - A circuit (10-22-2009
20120293256SWITCHING AMPLIFIER - When a switching amplifier transitions into a power-off state, a switch is turned off and a power supply controller forcibly discharges a capacitor and forcibly reduces a reference potential with respect to a second power supply voltage. Since a logic power supply voltage reduces by the same amount as the reference potential, the logic power supply voltage from a viewpoint of the reference potential is fixed. A constant current circuit reduces a constant current according to the reduction in the reference potential with respect to the second power supply voltage, and reduces a first electric current and a second electric current. Before the logic power supply voltage from the viewpoint of the reference potential reduces, the first electric current and the second electric current are reduced, and an operation of a pulse generating unit can be ended in a normal state.11-22-2012
20090128237SWITCHING AMPLIFIERS - Systems and methods implemented in a switching amplifier for providing consistent, matching switching between top and bottom switching devices in a switching amplifier. One embodiment includes a half-bridge circuit output stage, a driver stage and a transformer. The driver stage, which drives the switches of the output stage, is very fast, has a low propagation delay, and has minimal input capacitance. The transformer drives the drive paths from the transformer inputs to the switches. The transformer avoids resonances within the audio band and at the amplifier switching frequencies, has low and spread free leakage inductance, has enough magnetizing inductance to keep transformer currents low in proportion to the total driver stage current drain, has low core losses at the switching frequency, has minimal inductance change and operates well below its saturation point. The amplifier stage provides a substantially constant amplitude drive signal to the output power switching devices.05-21-2009
20100102881SAMPLING FREQUENCY REDUCTION FOR SWITCHING AMPLIFIERS - The present invention is directed toward providing a system and method of reducing RF interference in switching amplifiers without degrading performance. In one embodiment, the sampling rate of coarse high voltage modulated pulsewidths are decreased relative to the sampling rate of fine lower voltage modulated pulsewidths. This reduction in the sampling rate of coarse high voltage modulated pulsewidths results in a reduction in EMI. In addition, the higher sampling rate of the fine lower voltage modulated pulsewidths mitigates the distortion caused by the reduced sampling rate of the coarse pulsewidths.04-29-2010
20100102882ELECTRIC LOAD DRIVING CIRCUIT - An electric load driving circuit for driving an electric load having a capacity component includes a plurality of power sources generating different voltages, capacitors provided parallel to the plurality of power sources, a switch control unit that switches connections between the capacitors and the electric load and thereby switching a voltage applied to the electric load, discharge paths that enable discharging electric charge stored in the capacitor, and a discharge control unit that controls a quantity of electric charge discharged from the discharge paths.04-29-2010
20100102883PWM SIGNAL GENERATION CIRCUIT, CLASS-D AMPLIFIER AND METHOD FOR DRIVING THE SAME - A first situation indicating that the system is in a power-on situation or an un-mute situation, or a second situation indicating that the system is in a power-off situation or in a mute situation, is detected. When the first situation is detected, a differential PWM signal including a plurality of pulses each having a gradually increased or reduced width and the subsequent pulse train of 50% duty cycle pulses is generated and, if the output of an audio processor is in a stable situation, sent to the amplifier via a multiplexer. When the second situation is detected, the differential PWM signal including a plurality of pulses each having a gradually reduced width and the subsequent pulse train of no signal is generated and, at the same time, the generated pulses are sent to the amplifier via the multiplexer.04-29-2010
20080246542Amplifier for a radio frequency transmitter for transmitting a transmit signal to an otological apparatus - There is described an amplifier for a radio frequency signal for transmitting a transmit signal to an otological apparatus. The amplifier comprises at least one power transistor for switching an output signal. A breaker gap of the power transistor is actively connected to a network such that a power loss converted in the power transistor is at least partially reduced during a switchover into a switched-on state and/or at least during a switchover into a switched-off state. The breaker gap of the at least one transistor is at least indirectly connected in series to a power supply source by way of a choke coil. The amplifier comprises a transmit coil as an output load, with the transmit coil comprising an inductor and being actively connected to the power transistor. The transmit coil is coupled to the choke coil in a transformer-like manner, with the choke coil thus being able to transmit an output power to the transmit coil. The transmit coil can generate a transmit signal from the output power.10-09-2008
20090167436HIGH-EFFICIENCY SWITCHING POWER AMPLIFIERS WITH LOW HARMONIC DISTORTION - In one embodiment, a switching power amplifier is provided that includes: a power switch coupled between a power supply node and ground, wherein the power switch is configured to be cycled on and off responsive to an input signal voltage; and a matching network coupled between a terminal of the power switch and an output node, wherein the matching network includes: a first capacitor coupled between the terminal of the power switch and ground; a second capacitor having a first terminal and an opposing second terminal, the second terminal being coupled to ground, the second capacitor having a greater capacitance than the first capacitor; and a second switch coupled between the first terminal of the second capacitor and the terminal of the power switch, the second switch being configured to be cycled on and off responsive to a switching signal voltage such that the second switch is turned on before the power switch is turned off and such that the second switch is turned off after a current through the power switch is substantially zero responsive to the turning off of the power switch.07-02-2009
20080284511Device Comprising a Switching Amplifier and a Load11-20-2008
20100201445Class D Amplifier Having PWM Circuit With Look-Up Table - A class D amplifier includes a noise-shaping modulator, a pulse width modulator, and a pulse amplifier. The noise-shaping modulator receive a pulse code modulated (PCM) signal and produces an oversampled PCM signal. The pulse width modulator produce a pulse width modulated (PWM) signal from the oversampled PCM signal. The pulse amplifier amplifies the PWM signal to produce an amplified PWM signal. The PWM uses a lookup table to convert from PCM to PWM. A compensation circuit optimizes amplifier performance. An optional demodulator filter converts the amplified PWM signal to an analog signal. The amplifier is ideal for integrated audio applications.08-12-2010
20100201444Signal Modulation for Switched Mode Power Amplifiers - In a device (08-12-2010
20100201443REDUCTION OF DEAD-TIME DISTORTION IN CLASS D AMPLIFIERS - Pulse-width-modulating class D amplifier with an H-bridge output stage, and method of operating the same. in which output stage dead-time is compensated. Offset logic circuitry detects various dead-time-related conditions at push-pull output drivers, and generates an offset signal applied to the amplified differential input signal, to adjust the time at which the voltage at differential signal lines crosses a ramp reference waveform. The offset signal can correspond to the duration of a disturbance (dead-time at one driver in combination with an active signal at the active driver), or the sum of that disturbance duration with a dead-time at the active driver. The offset signal is generated by charging a capacitor for the duration of this disturbance, or disturbance plus dead-time. According to another approach, error is reduced by charging a capacitor for each transition of the signal for a duration of the dead-time of the active driver. Total harmonic distortion is reduced without requiring increased circuit complexity and without shortening the dead-time to unsafe margins.08-12-2010
20080303590POWER AMPLIFIER WITH NOISE SHAPING FUNCTION - A power amplifier with noise shaping function is provided. The power amplifier includes a differential mode integrator, an integration and adjustment unit and a switch unit. The differential mode integrator is used for receiving a differential mode input signal and a differential mode output signal, and outputting a differential mode first signal. The integration and adjustment unit is coupled to the differential mode integrator for receiving the first signal and an output signal and outputting a single-end mode second signal. The switch unit is used for receiving the second signal and outputting the differential mode output signal to drive the load. The present invention uses a common mode input signal instead of the single-end input signal to eliminate the common mode noise, and uses a 212-11-2008
20080272842Calibrated feedback - A differential feedback amplifier is provided with a feedback network wherein that feedback network is adjustable so as to improve the PSRR of the amplifier. In another aspect of the present invention, a differential feedback amplifier is provided with a feedback network wherein that feedback network is adjustable so as to improve the CMRR of the amplifier. In a further aspect of the present invention, a Class D amplifier is provided with a passive differential feedback, summing with an input current at a differential virtual ground produced by an amplifier which is a sub-section of the Class D amplifier.11-06-2008
20100289578MULTI-BIT CLASS-D POWER AMPLIFIER SYSTEM - Techniques for designing an efficient power amplifier are described. In one aspect, multiple single unit instance class-D power amplifiers with coupled outputs are utilized to increase efficiency and reduce quantization noise. In another aspect, multiple groups of single unit instance class-D power amplifiers are coupled at the outputs thereof with each group of power amplifiers configured to resonate at unique frequency. This results in increased efficiency and reduction of quantization noise at multiple frequencies bands.11-18-2010
20090309658METHOD AND APPARATUS FOR POWER CONVERTER FOR CLASS D AUDIO POWER AMPLIFIERS - A method and apparatus for power conversion in a class D amplifier is provided. The power conversion is achieved using synchronous rectifiers in a regulated half bridge power supply, taking the sum of the positive and negative rails as feedback, in order facilitate energy transfer between positive and negative output rails. This minimizes the effects of off side charging and rail sag, as well as achieving good line regulation, while allowing use of very small, low value output capacitors.12-17-2009
20110006844Class D Amplifier Control Circuit and Method - Circuit and method for a Class D amplifier. In one exemplary embodiment, an audio amplifier is disclosed. A closed loop configuration for driving high and low side driver transistors is provided, each circuit is compatible with advanced sub micron semiconductor processes. The analog time varying input is coupled to one input of a sigma delta analog to digital converter. A feedback signal from the output is also input to the analog to digital converter. A bit stream is output by the analog to digital converter. A decimator receives this bit stream and downconverts the samples to digital values at a lower frequency. A digital filter with adaptable coefficients is used to filter that signal and a digital pulse width modulator then develops an analog differential PWM signal. A predriver inputs the PWM signal and derives the output gating signals to control the high and low side drivers of a Class D amplifier.01-13-2011
20110006843Offset voltage correction circuit and class D amplifier - A class D amplifier includes an input unit that inputs an input signal and an integrator which includes a differential operational amplifier having an offset voltage correction function. The integrator integrates the input signal input. A pulse-width modulator modulates the integration result of the integrator to generate a pulse signal having a pulse width reflective of the integration result. An output unit outputs the pulse signal. A feedback unit superimposes a signal output from the output unit on the input signal and feeds back the superimposed signal to the integrator. An input controller selectively set the input unit to a state where no signal is input. An output controller sets a voltage of an output from the feedback unit to a constant voltage.01-13-2011
20090160552APPARATUS AND METHOD FOR CLASS D AMPLIFIER WITH SAMPLING RATE CONVERSION - A class D amplifier is provided. The class D amplifier includes an interpolator, a sampling rate converter, a pulse width modulator, a sigma-delta modulator, and a pulse width modulation (PWM) pulse generator (PPG). The sampling rate converter interpolates the output of the interpolator such that the sampling rate converter up-samples the interpolator output by a factor that is greater than one and less than two. The pulse width modulator outputs a multi-bit digital signal. The sigma-delta modulator performs sigma-delta modulation on the pulse width modulator output, the order of the sigma-delta modulation is programmable, and the output of the sigma-delta modulator is a multi-bit, digital signal. At least one of the orders to which the sigma-delta modulator can be programmed is greater than two. The PPG provides a pulse signal such that the width of each pulse is based on the value of the sigma-delta modulator output.06-25-2009
20090015327SWITCHING AUDIO POWER AMPLIFIER WITH DE-NOISE FUNCTION - The invention provides a switching audio power amplifier with de-noise function including a pulse width modulator, a de-noise circuit and a bridge circuit. The pulse width modulator performs pulse width moderation to generate the first and second PWM signals according to an input audio signal. The de-noise circuit receives the first and second PWM signals. And the bridge circuit conducts a driving current alternately flowing to and from a load according to the control signals output from the de-noise circuit.01-15-2009
20090251212SWITCHING AMPLIFIER - An amplifier having at least one switch controlled by an output voltage of a hysteresis block, wherein the hysteresis block is adapted to receive an input voltage signal based on an integration of an error signal, a low threshold voltage and a high threshold voltage, and is arranged to change the output voltage from a first value to a second value when the input voltage signal is higher than the high threshold voltage and to change the output voltage from the second value to the first value when the input voltage signal is lower than the low threshold voltage, and wherein the low threshold voltage is equal to V10-08-2009
20090051427OUTPUT LIMITING CIRCUIT, CLASS D POWER AMPLIFIER AND AUDIO EQUIPMENT - An output limiting circuit includes a reference current generating portion for converting a predetermined constant voltage into a reference current by using a first resistor, an upper side clip voltage generating portion for converting the reference current into an upper side clip voltage with respect to a bias voltage of the operational amplifier by using a second resistor, a lower side clip voltage generating portion for converting the reference current into a lower side clip voltage with respect to the bias voltage of the operational amplifier by using a third resistor, and a gain adjusting portion for adjusting a gain of the operational amplifier so that a voltage level of the output signal does not exceed an upper side limit level corresponding to the upper side clip voltage and that the voltage level of the output signal does not exceed a lower side limit level corresponding to the lower side clip voltage.02-26-2009
20110227645CLASS-D POWER AMPLIFIER - A class-D power amplifier includes a switching power source section, a synchronization signal generation section and a class-D power amplifying section. The synchronization signal generation section takes out of the switching power source section a clock signal having a second frequency which is “n” times of a first frequency. The class-D power amplifying section includes a comparator which compares an input signal with a feedback signal, a second switching section which switches a power source fed from the synchronization signal generation section, a filter section which smoothes an output signal from the second switching section, and a combining section which combines a delayed output signal with a clock signal from the synchronization signal generation section to generate the feedback signal. The class-D power amplifying section is adjusted so as to cause self-oscillating operation at a frequency substantially identical with the second frequency, when a level of the output signal from the filter section is low.09-22-2011
20090085659DIFFERENTIAL AMPLIFIER - An amplifier comprising an analog amplifier which outputs a first current and a second current. The amplifier also comprises a first digital amplifier coupled to the analog amplifier, the first digital amplifier amplifies a modified version of the first current to produce a third current. The amplifier also comprises a second digital amplifier coupled to the analog amplifier, the second digital amplifier amplifies a modified version of the second current to produce a fourth current. The amplifier also includes connections configured to provide the first, second, third and fourth currents through a load.04-02-2009
20090108932Signal generating apparatus and class-d amplifying apparatus - A signal generating apparatus includes: a data generator which generates a data series in which first, second, third and fourth data are arranged at a sampling period; a first signal generator which generates a first pulse-width modulation signal in which a pulse is arranged in a pulse period longer than the sampling period, time points of front and rear edges of the pulse being set in response to the first and second data; and a second signal generator which generates a second pulse-width modulation signal in which a pulse is arranged between the adjacent pulses of the first pulse-width modulation signal, time points of front and rear edges of the pulse of the second pulse-width modulation signal been set in response to the third and fourth data, respectively.04-30-2009
20090146737CLASS-D AMPLIFIER AND MULTI-LEVEL OUTPUT SIGNAL GENERATED METHOD THEREOF - A class-D amplifier and a method of generating a multi-level output signal thereof are provided. The class-D amplifier includes a controlling logic circuit and an output module. The controlling logic circuit analyzes the amplitude of an input signal to generate a voltage modifying signal. A power supply provides a voltage according to the voltage modifying signal. The controlling logic circuit generates controlling signals according to the input signal. The output module generates an output signal to drive a load according to the voltage and the controlling signals. In other words, the resolution of the amplitude of the output signal is increased by modifying the voltage, and a signal to noise ratio is then increased.06-11-2009
20090315623CLASS D AUDIO AMPLIFIER - A class D amplifier (12-24-2009
20100188150Switching Amplifier - A switching amplifier is disclosed and comprises: a power supply (Vcc); input circuits (Va, Vb); switch transistors (M07-29-2010
20100182084LOW RF INTERFERENCE SWITCHING AMPLIFIER AND METHOD - A switching amplifier includes first and second output terminals that may be connected to a load. A pulse-width modulator receiving an input signal to obtain respective positive and negative values of the input signal. The modulator is connected to first and second switching circuits. The first switching circuit applies a plurality of pulses to the first output terminal that, in response to the positive samples, have a constant frequency and are pulse-width modulated, and, in response to the negative samples, have a varying frequency and a constant width. Similarly, the second switching circuit applies a plurality of pulses to the second output terminal that, in response to the negative samples, have a constant frequency and are pulse-width modulated, and, in response to the positive samples, have a varying frequency and a constant width. The varying phase of the constant width pulses disperses RF interference across a wider spectrum.07-22-2010
20100182083AMPLIFIER CIRCUITRY - A class D amplification device that prevents beats caused by switching operations of a switching power supply and a class D amplifier from causing noise within a voice band, enables easy control over power supply operations, and offers low power loss is provided. The amplification device includes a unit that generates a reference clock, a switching power supply that operates at a first frequency at which the frequency of the reference clock is divided, and a triangular wave generation unit that operates at a second frequency higher than the first frequency at which the frequency of the reference clock is divided. The amplification device further includes a class D amplifier that performs a switching operation with a pulse whose width has been modulated according to the input signal.07-22-2010
20100253428PWM AMPLIFIER - Amplifier device of the pulse width modulation amplifier type (PWM amplifier), which comprises a switch according to a micro-electromechanical system (MEMS-switch) for a signal to be amplified (V10-07-2010
20100225391Three-level half-bridge pulse-width modulation amplifier and method of driving the same - A three-level half-bridge PWM amplifier includes a PWM generator and an output stage. The PWM generator changes a width of a pulse at a first level or a second level according to amplitude of an input signal and outputs a three-level PWM output signal having the first level, the second level, and a reference level. The output stage drives an output node connected to a terminal of a load to a first power supply voltage, a second power supply voltage, or a third power supply voltage based on the three-level PWM output signal. Accordingly, unnecessary static current consumption is reduced, thereby increasing efficiency.09-09-2010
20110057726SWITCHING AMPLIFIER - A switching amplifier (03-10-2011
20100253429METHOD FOR MEASURING THE SATURATION RATE OF AN AUDIO AMPLIFIER - A method and corresponding circuit that adjusts the gain of an audio output stage having a class D amplifier, this method including the steps of setting the gain to a nominal value, analyzing an output signal during successive clock periods, counting the number of clock periods during which the signal is in a state corresponding to a saturation, decreasing the gain if the number reaches, before the end of a first time interval, a value corresponding to a first percentage, maintaining the gain constant if, at the end of a second time interval, different from the first interval, the number corresponds to a second percentage being comprised between the first percentage and a third percentage, and increasing the gain if, at the end of the second time interval, the number corresponds to a fourth percentage, lower than the third percentage.10-07-2010
20090322426Output Short Circuit and Load Detection - One embodiment of an apparatus for testing an amplifier includes an amplifier having a driver and a filter, the filter being connected between an output of the driver and an output of the amplifier. The filter is operable to produce a demodulated output signal from a higher frequency modulated signal at the driver output. The apparatus also includes a voltage level detector connected to the driver output and a control circuit operable to detect at least one fault based on a voltage level measured at the driver output by the voltage level detector.12-31-2009
20090289710AMPLIFIER PROVIDING POWER RECOVERY FROM A NARROW-BAND ANTENNA - A method, amplifier and system are provided for enabling power recovery from a narrow-band antenna when a signal having bandwidth exceeding that of the antenna is utilized. The amplifier provides amplification of a source signal to the antenna and recovery of power stored in the antenna during periods when the impedance of the antenna is negative to enable reverse current through the amplifier to a direct current (DC) power source.11-26-2009
20100052783CLASS-D AMPLIFIER - An amplifier that receives an input signal and outputs an amplified output signal includes an integration stage, a comparison stage, and a full bridge circuit. The integration stage is be used for receiving a constant common mode voltage, for receiving a first signal representing the input signal of the amplifier, and for generating a ramp signal. The comparison stage coupled to the integration stage is used for generating a pulse width modulation signal according to the ramp signal and according to a hysteretic signal. The full bridge circuit coupled to the comparison stage is used for receiving a power supply and the pulse width modulation signal, and for generating the output of the amplifier.03-04-2010
20090072902LOW DISTORTION CLASS-D AMPLIFIER - An electronic class-D amplifier having an amplifier input to which an amplifier input signal may be applied, an amplifier output which may produce an amplifier output signal, an output switching stage, a pulse width modulator which includes an oscillator, wherein a first output of the oscillator produces a carrier reference signal, at least one servo-loop amplifier which includes an integrating feed forward transfer function, wherein the amplifier input is connected to an input of the servo-loop amplifier, a sample and hold element which includes a sample input and a control input, such that the sample and hold element samples a signal at the sample input when a sample command signal is applied to the control input, and the sample and hold element holds the value of the last sampled value of the signal at the sample input when the hold command signal is applied to the control input, and this said held value is applied to an output of the sample and hold element, the amplifier input is also connected to the sample input of the sample and hold element, an output of the sample and hold element is connected to a first input of an adder, and an output of the servo-loop amplifier is connected to a second input of the adder, an output of the adder is connected to a modulation input of the pulse width modulator, a second output of the oscillator is connected to the control input of the sample and hold element, an output of the pulse width modulator is connected to an input of the output switching stage, and an output of the output switching stage is connected to the amplifier output, wherein a negative feedback path connects an output of the output switching stage to an input of the servo-loop amplifier.03-19-2009
20110032034SWITCHED MODE AMPLIFIER - A switched mode amplifier includes a voltage source, a switched amplifier, a controller and a feedback unit. The switched amplifier sources or sinks a current to or from a load. The load and the current define a voltage over the load. The controller generates control signals for the switched amplifier in response to an input signal and a feedback signal. The feedback unit is connected to the controller and the load, and generates the feedback signal from the voltage over the load.02-10-2011
20110109386CLASS D AMPLIFIER CAPABLE OF SETTING RESTRAINT POWER - A Class D amplifier capable of setting restraint power is provided, which comprises: an audio amplification unit, a pulse width modulation (PWM) unit, a first pre-drive unit, a second pre-drive unit, a first power transistor set, a second power transistor set and a power restraint unit. The power restraint unit has a comparator circuit and a power restraint circuit. The comparator circuit is configured to compare the level of first/second amplified audio signals against the level of a first reference voltage that is externally settable. When the high level of the first/second amplified audio signals is higher than the level of the first reference voltage, the comparator circuit outputs a first comparison signal and a second comparison signal to the power restraint circuit to restrain the power.05-12-2011
20110109387Power amplification apparatus for envelope modulation of highfrequency signal and method for controlling the same - A power amplification apparatus and method provide for controlling envelope modulation of a Radio Frequency (RF) signal. The power amplification apparatus includes a linear amplifier configured to receive an input signal to be amplified, and generate a linear output signal for compensating for a current ripple of an amplified signal and a switch control signal having a current obtained by dividing the linear output signal by a predetermined ratio. The power amplification apparatus also includes a switching amplifier configured to receive the switch control signal through a multi-mode resistor having a variable resistance, and generate the amplified signal. The variable resistance of the multi-mode resistor determines a switching frequency representing an operating speed of the switching amplifier, and is adjusted according to a communication mode of the input signal.05-12-2011
20110025415Digital Modulated RF Power Amplifier with Impedance Compensation Circuit - A digital modulated power amplifier unit includes a differential radio frequency (RF) amplifier circuit having differential output nodes, a digital modulation signal input and complimentary clock signal inputs. The differential RF amplifier circuit includes a first pair of transistors operable to receive a digital modulation signal and a second pair of transistors operable to receive complimentary clock signals. The digital modulated power amplifier unit further includes an impedance compensation circuit connected between the differential output nodes of the differential RF amplifier circuit. The impedance compensation circuit includes a transistor connected in series between first and second RC circuits. The transistor is operable to electrically connect and disconnect the first RC circuit and the second RC circuit responsive to the digital modulation signal.02-03-2011
20110037517Concept, method and apparatus of improved distortion switched-mode amplifier - Systems and methods for switched-mode amplifiers having improved harmonic distortion are disclosed. High order in-band filtering is enabled without undue trade-off of distortion due to intermodulation/aliasing. A pre-modulation block is introduced, deployed between a loop filter block and a pulse-width modulation block, performing uniform pulse-width modulation. The pre-modulation block attenuates/removes amplitude dependent high frequency ripples before pulse-width modulation. The pre-modulation block in conjunction with the pulse-width modulation block performs double sampling of the input signals.02-17-2011
20120242407Switched Amplifier Circuit Arrangement and Method for Switched Amplification - A switched amplifier circuit arrangement comprises a main amplifier (Amp) having an input terminal (In) and an output terminal (Out) and a regulating amplifier (rAmp) to set an input and an output operating point of the main amplifier (Amp). The regulating amplifier (rAmp) exhibits an auxiliary amplifier (A) having a first input terminal coupled to a reference level (Vref), a second input terminal (Ain) coupled to the output terminal (Out), and an output terminal (Aout) which is connected via a first switch (S09-27-2012
20100033248Power Amplifier and Common Mode Choke Coil Apparatus - Common mode choke coil device includes four coils wound on a core in a same direction. Hot-side outputs of first and second class-D amplifiers are connected to respective ones of first ends of two of the four coils, and first and second hot-side output terminals are connected to respective ones of second ends of the two coils. Ground-side outputs of the first and second class-D amplifiers are connected to respective ones of the first ends of remaining two of the four coils, and first and second ground-side output terminals are connected to respective ones of the second ends of the remaining two coils. Single-end connection is realized by connecting a separate load to each of the class-D amplifiers via the corresponding first (or second) hot-side and ground-side output terminals. BTL connection is realized by connecting a single load to the class-D amplifiers via the first and second hot-side output terminals.02-11-2010
20100066446CLASS-D AMPLIFIER - The invention describes a power amplifier comprising a first transistor (M03-18-2010
20110068870CLASS-D AMPLIFIER WITH DUAL FEEDBACK LOOP - A class-D amplifier with dual feedback loop scheme has a gain adjusting circuit, a second-order integrator, two comparators, a logic circuit and an output driver. Two differential output terminals of the class-D amplifier are connected to two differential amplifiers of the second-order integrator to construct a second-order feedback loop for offering second order noise shaping, eliminating non-linear components in the class-D amplifier, and also enhancing signal to noise and distortion ratio (SNDR). Further, distortion component existing in the differential signal output from the differential output terminals is amplified by the two differential amplifiers so as to improve the loop gain of the class-D amplifier. The differential signal processed by the two differential amplifiers also can be precisely adjusted.03-24-2011
20090027121Class D amplifier circuit - A pulse monitor circuit detects the presence or non-presence of the output pulses output from an output stage circuit. The pulse monitor circuit outputs an up signal to the up/down counter when the output pulses do not exist at all and outputs a down signal to the up/down counter when the output pulses exist. The up/down counter outputs a signal for increasing the delay amount of a delay amount variable circuit when a count value is large, that is, when the output pulses disappear. In contrast, when the count value is small, that is, when the output pulses exist, the counter outputs the signal for reducing the delay amount of the delay amount variable circuit.01-29-2009
20110248781Duplicate feedback network in class D amplifiers - A circuit and a method are provided for suppressing the pop and click noise during the power on and power off of Class D amplifiers. The technique also suppresses pops and clicks when the Class D amplifier enters or exits standby mode. A duplicate feedback network is used to establish the stable operating points, including offsets in the Class D circuit without turning on the outputs. The technique works by gradually propagating or dissipating the offset through the signal path of a Class D amplifier by swapping the differential outputs using switches to suppress pops and clicks when starting up and shutting down the amplifier.10-13-2011
20090231035CLASS D AUDIO AMPLIFIER - A class D audio amplifier includes an error amplifier, a comparator, a bridge circuit, a feedback circuit and a silent start circuit. The error amplifier generates an error signal by amplifying a difference between a feedback signal and an audio input signal. The comparator generates a first pulse width modulation (PWM) signal by comparing a first triangular-wave signal and the error signal. The bridge circuit has switches alternately conducting a current flowing into and from a load. The feedback circuit generates the feedback signal indicating a condition of the load. The silent start circuit performs AND operation of the first PWM signal and a second PWM signal having a gradually increased duty ratio to generate a third PWM signal for control of the switches of the bridge circuit.09-17-2009
20090184765CLASS-D AMPLIFIER AND METHOD THEREFOR - In one embodiment, a class-D amplifier (07-23-2009
20100321111POWER AMPLIFIER - The invention refers to a power amplifier comprising a first transistor (M12-23-2010
20110254625CIRCUIT AND METHOD FOR REDUCING NOISE IN CLASS D AMPLIFIERS - A circuit for reducing noise in Class D amplifiers has a power stage voltage control means (10-20-2011
20110133836CLASS-D AMPLIFIER - Class D amplifier is provided. The class D amplifier includes at least a block; each block includes an input circuit, an integrator, a comparator, a driving circuit and two feedback circuits. The input circuit receives a digital input to provide a differential pair of a positive and a negative input signals. The integrator receives the positive and negative input signals and a pair of positive and negative feedback signals for providing a positive error signal according to the positive input signal and the negative feedback signal, and providing a negative error signal according to the negative input signal and the positive feedback signal. The comparator compares between the positive and the negative error signals such that the driving circuit generates a driving output signal according to comparison result. The two feedback circuits respectively providing said positive and negative feedback signals according to the driving output signal.06-09-2011
20100253427CLASS-D AMPLIFIER - The invention discloses a class-D amplifier, which is used for driving a two-terminal load according to a set of analog signals. The D-class amplifier includes a pulse-width modulation (PWM) circuit, a signal processing circuit and a driving amplifier circuit. The PWM circuit receives the set of analog signals and converts them into a set of PWM signals with identical phase. The signal processing circuit generates a set of pulse signals which are attached to the set of PWM signals respectively. The driving amplifier circuit is coupled between the signal processing circuit and the two-terminal load. The driving amplifier circuit receives and amplifies the set of PWM signals. According to the set of PWM signals, the driving amplification circuit drives the two-terminal in a filterless way.10-07-2010
20110260793Ground-referenced common-mode amplifier circuit and related method - Disclosed is an amplifier circuit configured to amplify a pulse stream. The amplifier circuit comprises a switching block including a first switch operable to couple an output node of the switching block to a positive reference voltage, a second switch operable to couple the output node to a ground reference voltage and a third switch operable to couple the output node to a negative reference voltage. The amplifier circuit is configured to amplify the pulse stream into an amplified signal detectable at the output node such that the amplified signal has a common-mode voltage level substantially equal to zero volts. In one embodiment, the amplifier circuit is configured to amplify the pulse stream in accordance with a Class-D amplification scheme. In one embodiment, the output node can be directly connected to a load device without a DC blocking capacitor being interposed between the output node and the load device.10-27-2011
20100176881PULSE WIDTH MODULATION CIRCUIT AND CLASS-D AMPLIFIER COMPRISING THE PWM CIRCUIT - A pulse width modulation (PWM) circuit comprises a first integrator (g m07-15-2010
20080218264CLASS D AMPLIFIER ARRANGEMENT - An amplifier arrangement for operation at supply voltages of at least 100V and at output powers of at least 1 kW includes a half-bridge formed from two switching elements connected in series, two supply voltage terminals, and an output connection between the switching elements. A bypass capacitor is in parallel with the switching elements, and a current path is through the switching elements and the bypass capacitor, where the current path has a length of 10 cm or less, the half-bridge and the bypass capacitor are arranged on an area of 30 cm2, and a resonant circuit formed by capacitances and inductances in the current path has a resonance frequency of 100 MHz or greater.09-11-2008
20110148521DYNAMIC CONSTANT POWER AMPLIFIER - A switching amplifier including a voltage sensor circuit connected to a high voltage supply rail for measuring the power supply voltage. A current sensor circuit is connected to the high voltage supply rail for measuring the power supply current. An error amplifier is connected to the switching amplifier and receives one or more values based on the measurements taken by the voltage sensor and current sensor, and the error amplifier produces an error signal when a predetermined power limit is exceeded. A signal limiting circuit is connected to the error amplifier and the switching amplifier and limits the output power to rated power at any rated load impedance when the error amplifier produces the error signal. This switching amplifier is capable of automatically limiting output power at rated power into all rated load impedances, and dynamically reacts to the frequency-dependant impedance of a typical audio system.06-23-2011
20100019846AMPLIFIER EMPLOYING INTERLEAVED SIGNALS FOR PWM RIPPLE SUPRESSION - An amplifier having improved distortion characteristics is set forth. The amplifier includes an interleaved PWM amplifier that generates interleaved PWM pulses in response to a modified input signal and one or more carrier signals. The interleaved PWM pulses of the amplifier are used to drive a power stage, such as an opposed current power stage. The amplifier also includes an interleaved PWM generator that provides interleaved PWM pulses in response to the modified input signal and one or more further carrier signals. The carrier signals used by the PWM generator may differ in phase from the carrier signals used by the interleaved PWM amplifier to generate its interleaved PWM pulses. One or more feedback circuits are employed in the generation of the modified input signal. More particularly, the feedback circuit(s) generates the modified input signal based on an input signal that is to be amplified and the interleaved PWM pulses of the interleaved PWM generator.01-28-2010
20090174478Circuit and method for generating a PWM control signal for a class-D amplifier - In a class-D amplifier, the input signal is compared with a carrier signal to generate a basic PWM signal, the PWM signal is then sent to a pulse processing unit, and by comparing with a basic periodic signal, half-width of the output PWM signal is extracted. Then, in the pulse processing unit, the half-width PWM pulse signal is used to generate a complete pulse whose width equals to the output PWM signal. The output power of the class-D amplifier can be kept as large as that by using differential input signals although the input signal is single-end and the entire signal processing path is kept single-ended.07-09-2009
20110316627DYNAMIC CONSTANT POWER AMPLIFIER - A switching amplifier including a voltage sensor circuit connected to a high voltage supply rail for measuring the power supply voltage. A current sensor circuit is connected to the high voltage supply rail for measuring the power supply current. An error amplifier is connected to the switching amplifier and receives one or more values based on the measurements taken by the voltage sensor and current sensor, and the error amplifier produces an error signal when a predetermined power limit is exceeded. A signal limiting circuit is connected to the error amplifier and the switching amplifier and limits the output power to rated power at any rated load impedance when the error amplifier produces the error signal. This switching amplifier is capable of automatically limiting output power at rated power into all rated load impedances, and dynamically reacts to the frequency-dependant impedance of a typical audio system.12-29-2011
20110012676SYSTEMS AND METHODS OF REDUCED DISTORTION IN A CLASS D AMPLIFIER - Systems and methods for reduced distortion in a class D amplifier are provided. An “ideal” digital output signal is produced. The “ideal” digital output signal is then compared to the actual output signal in an error amplifier. The integrator input is the difference between the output stage waveform and the ideal output stage waveform. The net input to the integrator now comprises the imperfections of the power stage, and the feedback loop drives their average to zero. This error is then amplified and integrated. The integrated signal is than applied to a summer where it is added to the analog input. Then as in the typical Class D amplifier, the integrated signal is compared in an error amplifier to a ramp signal generated from the ramp generator.01-20-2011
20100097139ERROR CORRECTION SYSTEM FOR A CLASS-D POWER STAGE - The present invention relates to a method for correcting for a source of non-linearity and noise introduced in a switching power amplification stage during power amplification of a pulse-modulated reference signal from a pulse modulator, where the method comprises the following steps: —providing an output stage embedded in an analogue self-oscillating control loop able to receive a pulse-referenced input signal; —generating a feedback signal from the switching power amplification stage or after a demodulation filter; —deriving an error signal by comparing the feedback signal with the reference signal; —filtering the error signal by a low pass filter for reducing the higher harmonics of the carrier; —adding a compensator for generating high loop gain in the audio band; —feeding the compensator output to a zero cross detector or comparator, thus providing a carrier for re-modulation or re-timing by feeding the filtered signal to a zero cross detector or comparator, which controls the output stage. The invention furthermore relates to various systems for implementing the above method.04-22-2010
20120044020METHOD AND APPARATUS FOR SENSING A CURREN FOR VARYING IMPEDANCE LOADS - Recently, there has been an increased desire to measure load currents of class-D amplifiers to improve performance. The traditional solution has been to include one or more discrete components in series with the load, but this degrades performance. Here, however, circuit is provided (which includes sample-and-hold circuit) that accurately measures load currents without inhibiting performance and that is not inhibited by the phase differences between the load voltage and load current.02-23-2012
20120056670CROSS CURRENT MINIMIZATION - A method of optimising cross current in class D amplifiers and simultaneously minimizing the harmonic distortion is provided. The method overcomes the problem of using the limited speed voltage comparators often used in cross current preventing circuits. Method embodiments are based on introducing a replica amplifier with a current sensor matched to a main amplifier. The duration of a sensed cross current within the replica amplifier is compared by a current comparator with a small enough reference current. The comparator output generates a pulse with a duration equal to the duration of the cross current event in the replica amplifier. The duration of that pulse is measured and used to generate a dead time pulse for blanking amplifier pre-driver inputs.03-08-2012
20120154043HIGH-FREQUENCY POWER AMPLIFIER DEVICE - Disclosed is a high-frequency power amplifier device capable of reducing a talk current. For example, the high-frequency power amplifier device has first and second power amplifier circuits, first and second transmission lines, and a region in which the first and second transmission lines are disposed close to each other. Either the first or second power amplifier circuit becomes activated in accordance with an output level. When the second power amplifier circuit is activated, currents flowing in the first and second transmission lines are transmitted in the same direction so that magnetic coupling occurs to strengthen each transmission line's magnetic force. When, on the other hand, the first power amplifier circuit is activated, currents flowing in the first and second transmission lines are transmitted in the opposite directions so that magnetic coupling occurs to weaken each transmission line's magnetic force.06-21-2012
20120025910Switching amplifier with enhanced supply rejection and related method - Disclosed is a switching amplifier having an enhanced supply rejection. The switching amplifier comprises a digital modulator that provides a modulated signal. The switching amplifier further comprises a closed-loop analog driver that is coupled to the digital modulator. As disclosed, the closed-loop analog driver is configured to re-modulate a modulation signal that corresponds to the modulated signal. An output stage of the switching amplifier is driven by the re-modulated signal, thereby providing enhanced supply rejection. In one embodiment, the modulated signal is produced by a digital pulse-width modulator (PWM) circuit of a Class-D amplifier, and has a pulse rate substantially less than a clock rate of the digital PWM circuit. In one embodiment, the switching amplifier is implemented as an audio amplifier in a mobile communication device such as a cellular telephone.02-02-2012
20120154044Class-D Amplifier Circuit - A class-D amplifier circuit includes an amplifier that generates pulse-width modulated output signals according to input signals which have phases reverse to each other and are supplied to a first input end and a second input end, a first transistor interposed between a first input path extending from the first input end to the amplifier and a second input path extending from the second input end to the amplifier, and a voltage applying circuit that applies a control voltage corresponding to a predetermined value to a control terminal of the first transistor so that a current flowing between both ends of the first transistor increases in accordance with increase of levels of the input signals within a range in which the levels of the input signals are higher than the predetermined value.06-21-2012
20100013555POWER AMPLIFIER - A driver (Highside Driver, Lowside Driver) adapted to drive each of final transistors (M01-21-2010
20100244958Class D amplifier circuit - A class D amplifier circuit includes a signal generation section that generates a first pulse width modulation signal and a second pulse width modulation signal based on an input signal. When a level of the input signal is zero, the signal generation section generates: the first pulse width modulation signal having a repeated first wide-width pulse signal portion, which has a wide width and a repeated first narrow-width pulse signal portion, which has a narrow width which is narrower than the wide width of the first wide-width pulse signal; and the second pulse width modulation signal having a repeated second narrow-width pulse signal portion, which has a narrow width and a repeated second wide-width pulse signal portion, which has a wide width which is wider than the narrow width of the second narrow-width pulse signal portion. A rising point in time of the second narrow-width pulse signal portion occurs after a rising point in time of the first wide-width pulse signal portion and a falling point in time of the second narrow-width pulse signal portion occurs before a falling point in time of the first wide-width pulse signal portion. A rising point in time of the first narrow-width pulse signal portion occurs after a rising point in time of the second wide-width pulse signal portion and a falling point in time of the first narrow-width pulse signal portion occurs before a falling point in time of the second wide-width pulse signal portion.09-30-2010
20110181356SWITCHING DEVICE OF DIGITAL AMPLIFIER AND METHOD FOR DRIVING THE SAME - A switching device of a digital amplifier and a method for controlling the same are disclosed. In accordance with the present invention, a linearity is maintain even for a short pulse width since a data signal having a pulse width shorter than a predetermined length. Moreover, when an MLP signal is located at both sides of a compensating signal without overlapping with each other, a problem due to a common mode may be prevented.07-28-2011
20120169420CIRCUIT AND METHOD FOR AMPLIFYING A DIGITAL SIGNAL - An amplifier circuit includes an amplifier unit that is configured to receive an input signal and generate a switching output signal. A level shifter is configured to shift the amplitude of the input signal to have a shifted amplitude that is proportional to a peak-to-peak amplitude of the switching output signal.07-05-2012
20090102557Class D amplifier - The invention is directed to a class D amplifier. According to the class D amplifier, sound data applied to an input terminal is supplied through a compensation circuit to a PWM circuit, from which a PWM signal is output. The PWM signal is converted to an analog signal through a first low pass filter, which is delivered to a speaker. On the other hand, the sound data is delayed by a delay circuit, and is converted to an analog signal by a digital to analog converter. The higher frequency components of the data are removed by a second low pass filter, and the rest of the data is furnished to a differential amplifier. The differential amplifier amplifies a difference between an output of the first low pass filter and an output of the second low pass filter, which is then supplied to an analog to digital converter. The analog to digital converter converts an output from the differential amplifier to digital data, which is then supplied to the compensation circuit. By doing so, a compensation value based on an output from the analog to digital converter is added to the following PCM sound data that is applied to the input terminal.04-23-2009
20120182069AMPLIFIER SYSTEM FOR A POWER CONVERTER - An amplifier system for a power converter includes at least a first switching device and a second switching device formed in an integrated circuit in a substrate of a semiconductor. The first and second switching devices may be formed in a half bridge configuration and may be cooperatively switchable to generate an amplified output signal on an output node of the semiconductor. A resistor and a capacitor may be coupled in parallel between a power supply input node and a substrate node included in the semiconductor. The capacitor may be selectively charged to a de-biasing voltage during a switching cycle of the first and second switching devices to reverse bias a parasitic switching device appearing in the integrated circuit.07-19-2012
20090021305Class D amplifier - Class D amplifier is resistant to interferences. Binary output signals y01-22-2009
20120299652MULTI-AUTONOMOUS ELECTRONIC AMPLIFIER - An electronic amplifier includes a configurable integrated circuit device structured to synthesize at least a first signal and a second signal, scale the first signal to create a scaled first signal and scale the second signal to create a scaled second signal, create a discrete time composite signal which comprises a summation of at least the scaled first signal and the scaled second signal, create a discrete time pulse width modulated signal based on the discrete time composite signal, and generate a number of control signals based on the discrete time pulse width modulated signal. The electronic amplifier also includes a power switching stage receiving the number of control signals from the configurable integrated circuit device, wherein the number of control signals are configured to control the power switching stage, and a low pass filter coupled to an output of the power switching stage.11-29-2012
20120229211AMPLIFIER USING FAST DISCHARGING REFERENCE - Techniques are disclosed relating to charging and discharging a gate of transistor. In one embodiment, an apparatus is disclosed that includes a driver configured to discharge a gate of a transistor. The driver is configured to discharge the gate at a first rate until reaching a Miller plateau for the transistor, and to discharge the gate at a second rate after reaching the Miller plateau. In such an embodiment, the first rate is greater than the second rate. In some embodiments, the driver is also configured to charge the gate of the transistor at a third rate until reaching a Miller plateau for the transistor, and to charge the gate at a fourth rate after reaching the Miller plateau, the third rate being greater than the fourth rate. In some embodiments, the apparatus is a class D amplifier.09-13-2012
20100327973AMPLIFIER CIRCUIT COMPRISING CHARGE PUMP AND LOW-PASS FILTER - According to one embodiment, an amplifier circuit includes a clock generation circuit, a switching amplifier circuit, and a smoothing circuit. The clock generation circuit generates a pseudo random period pattern signal whose period varies. The switching amplifier circuit samples an input signal based on the pseudo random period pattern signal used as a sampling clock. The smoothing circuit smoothes an output signal of the switching amplifier circuit.12-30-2010
20100327972Time Delay Compensation and Pulse Width Correction - A system, method and apparatus is provided for pulse width correction in a power driver. In an embodiment, an apparatus includes an operational amplifier having an input and an output. The input of the operational amplifier is coupled to receive an input pulse signal. The apparatus further includes an output stage having an input coupled to the output of the operational amplifier. The output stage also includes a current output configured to couple to a load and to a voltage sense output. The apparatus also includes a comparator having an inverting input coupled to the voltage sense output of the output stage, a non-inverting input configured to couple to an input signal, and an output. Also, the apparatus includes a timing circuit with an input coupled to the output of the comparator and an input coupled to the input signal. The timing circuit also has an output to supply the input pulse signal. The timing circuit measures a delay from a change in the input signal to a change in the output of the comparator. The timing circuit replicates the measured delay as a delay in a change to the input pulse signal.12-30-2010
20120326784POWER AMPLIFIER - A power amplifier includes: an input terminal at which an input signal is input; a first amplifier element amplifying the input signal; a second amplifier element amplifying an output signal of the first amplifier element; an output terminal from which an output signal of the second amplifier element is output; a matching circuit connected between an output of the second amplifier element and the output terminal; a first switch connected between an output of the first amplifier element and an input of the second amplifier element; and a second switch having a first end connected to the output of the first amplifier element, and a second end. The matching circuit includes a first inductor and a first capacitor connected in series between the output of the second amplifier element and a grounding point. The second end of the second switch is connected to a connecting point of the first inductor to the first capacitor.12-27-2012
20120081179DUTYCYCLE ADJUSTMENT TO IMPROVE EFFICIENCY OF A DIGITAL RF-PA - An amplification unit reduces a duty cycle of a digital signal at a carrier radio frequency to optimize the efficiency of the RF power amplifier that amplifies the reduced duty cycle signal. An exemplary amplification unit includes a duty cycle controller and a digital power amplifier. A delay unit in the duty cycle controller applies a delay to an input digital signal at the carrier radio frequency to generate a delayed signal at the carrier radio frequency. A logic gate in the duty cycle controller logically combines the input digital signal with the delayed signal to generate a modified digital signal at the carrier radio frequency, where the modified input digital signal has a reduced duty cycle relative to that of the input digital signal. Amplifying the modified digital signal in the digital RF power amplifier generates an amplified analog signal at the carrier radio frequency while improving amplifier efficiency.04-05-2012
20100231298Class D amplifier circuit - A class D amplifier circuit for generating a pulse signal whose pulse width is modulated in response to an input signal, the class D amplifier circuit includes first to fifth switching elements, a first capacitance element and a control section. The control section controls transition between a conduction state and a non-conduction state of each of the first to fifth switching elements to control a current direction flowing into a load having a first end electrically connected to the output end and a second end set to the reference potential, so that the current flows from the first end of the load to the second end of the load at a first timing and the current flows from the second end of the load to the first end of the load at a second timing.09-16-2010
20100231297ELECTRONIC DEVICE FOR SELF OSCILLATING CLASS D SYSTEM - The present invention relates to an electronic device that includes an integrated power comparator circuit (09-16-2010
20110260794HIGH FREQUENCY POWER AMPLIFIER - A high frequency power amplifier includes first and second transistors connected in parallel and amplifying a high frequency signal; a first switch connected to outputs of the first and second transistors and which connects an input terminal selectively to first and second output terminals; a third transistor amplifying a signal output from the first output terminal of the first switch; and a second switch having a first input terminal connected to the third transistor, a second input terminal connected to the second output terminal of the first switch, and which selectively connects the first and the second input terminals to an output terminal of the second switch.10-27-2011
20120326783LOW-VOLTAGE POWER-EFFICIENT ENVELOPE TRACKER - Techniques for efficiently generating a power supply are described. In one design, an apparatus includes an envelope amplifier and a boost converter. The boost converter generates a boosted supply voltage having a higher voltage than a first supply voltage (e.g., a battery voltage). The envelope amplifier generates a second supply voltage based on an envelope signal and the boosted supply voltage (and also possibly the first supply voltage). A power amplifier operates based on the second supply voltage. In another design, an apparatus includes a switcher, an envelope amplifier, and a power amplifier. The switcher receives a first supply voltage and provides a first supply current. The envelope amplifier provides a second supply current based on an envelope signal. The power amplifier receives a total supply current including the first and second supply currents. In one design, the switcher detects the second supply current and adds an offset to generate a larger first supply current than without the offset.12-27-2012
20100219891Class-D amplifier - A class-D amplifier includes a differential integrator that integrates a difference between an input signal and a feedback signal to output an integration value signal, a pulse width modulation circuit that outputs a digital signal having a pulse width corresponding to a level of the integration value signal, an output buffer that drives a load based on the digital signal, a feedback section that feeds an output signal of the output buffer into the differential integrator as the feedback signal, a clamp section that performs a clamping of limiting the level of the integration value signal within a specified level range, an attenuation section that attenuates the level of the input signal to be input to the differential integrator in response to an attenuation command, and an attenuation control section that outputs the attenuation command to the attenuation section in response to the clamping performed by the clamp section.09-02-2010
20120286868CLASS D POWER AMPLIFIER - A class D power amplifier (PA) is provided. The PA generally comprises a driver, output capacitor, a matching network, and a cancellation circuit. The driver has an input, an output, and a parasitic capacitance, and the input of the driver is configured to receive complementary first and second radio frequency (RF) signals, where there is a free-fly interval between consecutive pulses from the first and second RF signals. The output capacitor and cancellation circuit are each coupled to the output of the driver such that the cancellation circuit provides harmonic restoration at least during the free-fly interval, and the matching network is coupled to the output capacitor.11-15-2012
20130021096DIGITAL AMPLIFIER - A digital amplifier comprises: a switching unit that amplifies a signal input to the digital amplifier by performing a switching operation; a driving unit that turns the switching unit on and off; an input signal detection unit that detects an input signal to the digital amplifier; and a first control unit that performs control such that the switching unit starts a switching operation by starting driving of the driving unit, when the digital amplifier is changed to a signal input state and the input signal detection unit detects an input signal, and performs control such that the switching unit stops the switching operation by stopping the driving of the driving unit, when the digital amplifier is changed to a no signal input state and the input signal detection unit does not detect an input signal. This configuration enables to reduce power consumption when no signal is input.01-24-2013
20080252372Power-MOSFETs with Improved Efficiency for Multi-channel Class-D Audio Amplifiers and Packaging Thereof - A stereo class-D audio system includes a first die including four monolithically integrated NMOS high-side devices and a second a second die including four monolithically integrated PMOS low-side devices. The audio system also includes a set of electrical contacts for connecting the high and low-side devices to components within the a stereo class-D audio system, the set of electrical contacts including at least one supply contact for connecting the drains of the high-side devices to a supply voltage (V10-16-2008
20080224773Digital input class-D amplifier - A digital input class-D amplifier includes a decoder which outputs a plurality of lines of time-series digital signals having a density of 1 or 0 conforming to an input digital signal, an error integrator which integrates a difference between a drive waveform to be applied to a load and a sum of the plurality of lines of time-series digital signals output from the decoder, and a modulation circuit which generates a pulse modulated with a pulse width or a pulse density based on a result of integration performed by the error integrator. The load is driven in accordance with the pulse generated by the modulation circuit.09-18-2008
20130113561OUTPUT MODE SWITCHING AMPLIFIER - An output mode switching amplifier, including: a transistor for signal amplification connected between a first node on an input side and a second node on an output side; a bypass path for bypassing the transistor between the first node and the second node; a voltage control circuit for switching whether to apply a bias voltage to the transistor so that a transmission signal is amplified by the transistor or to output a transmission signal via the bypass path without amplifying the transmission signal by the transistor; and a second-harmonic reflection circuit connected to the bypass path, for reflecting a second harmonic of the transmission signal.05-09-2013
20130127532SWITCHED-MODE POWER SUPPLY APPARATUS AND METHOD - The present invention relates to a switched-mode power supply apparatus and a corresponding method. For an effective compensation of non-linearities caused by dead-time and voltage drops in the switching power amplifier of the apparatus, an apparatus is proposed comprising a switching power amplifier (05-23-2013
20130127530MULTI-LEVEL BOOSTED CLASS D AMPLIFIER - Techniques to generate boosted multi-level switched output voltages from a boosted multi-level Class D amplifier. The amplifier may include a multi-level H-bridge, which may include pairs of transistor switches coupled to a first, second, and third supply potential. The second supply potential may be a boosted representation of the first supply potential. The amplifier may receive an input signal, and from the input signal may generate pulse-modulated control signals to control the switching for the transistor switches of the multi-level H-bridge. The amplifier may generate the boosted multi-level switched output voltages from output nodes of the multi-level H-bridge.05-23-2013
20130127531AMPLIFIER CIRCUIT WITH OFFSET CONTROL - Methods and apparatus for Class-D amplifier circuits with D.C. offset control/correction. A Class-D amplifier is described having an output stage, such as a full H-bridge or half bridge, with a plurality of switches operable to provide a plurality of output states comprising at least a positive output state and a negative output state. Control circuitry is configured to receive a first signal based on the input signal and produce a digital control signal, which is used to determine the switch state of the output stage. A digital integrator is configured to receive a feedback signal indicative of the output state of the output stage and to sample the feedback signal at a sample rate and produce an integrated output signal (INT, IVC) indicating the difference in number of instances of the positive output state and the negative output state. Correction circuitry subtracts the integrated output signal from the input signal to produce a D.C. offset corrected signal.05-23-2013
20130135046SWITCHING CIRCUIT AND ENVELOPE SIGNAL AMPLIFIER - A switching circuit 05-30-2013
20130141162SWITCHING AMPLIFIER WITH INDUCTANCE MEANS FOR TRANSMITTING ENERGY - A switching amplifying method or a switching amplifier for obtaining one or more linearly amplified replicas of an input signal, is highly efficient, and does not have the disadvantage of “dead time” problem related to the class D amplifiers. Said switching amplifier comprises: an inductance means; a switching unit for switching a current from a DC voltage to the inductance means; a switching power transmitting unit for blocking a current when the switching unit switches on, and conducting the current from the inductance means to a filter unit positively or negatively according to the polarity of the input signal when the current from the DC voltage to the inductance means is switched off; an amplifier control unit to control the switching unit and the switching power transmitting unit according to the input signal; said filter unit filtering the current from the switching power transmitting unit to get an output signal.06-06-2013
20100277238Hybrid Feedback Controlled Oscillation Modulator and Switching Power Amplifier System - A Hybrid feedback Controlled Oscillation Modulator (HCOM) is disclosed, having a 111-04-2010
20100033247TRUE CURRENT LIMITING - The invention relates to a current limiting method, e. g. for Class D amplifiers comprising a unique detection- and control method. The current detection circuit can be implemented as a voltage measurement where the measured voltage corresponds to the current flowing through the power-switching device. The device can be switched OFF when a set limit is reached. By forcing certain OFF time, the associated control system behaves as a self-oscillating current limiting circuit. This can be implemented locally close to the switching device and be independent of other local or global control systems.02-11-2010
20110215867REDUCING PULSE ERROR DISTORTION - A class D amplifier that includes circuitry to apply a non-linear correction to pulse error distortion. The amplifier includes an output voltage controlling circuit, comprising at least two switches, controlled by a modulator; an output inductor, coupling the switching circuit to an output terminal; and correction circuitry to provide to the modulator a correction signal characterized by a non-linearity. The correction circuitry includes a current sensor that senses the current from the output inductor to the output terminal.09-08-2011
20110210790FILTER COMPENSATION FOR SWITCHING AMPLIFIERS - Embodiments of the present invention provide methods and systems for limiting bipolar current flow in a switching amplifier. Embodiments of the present invention are directed to a multi-referenced switching amplifier. In some embodiment, the switching amplifier is a dual referenced switching amplifier comprising a regulator between the two references, where the first reference provides coarse modulation to a load and the second reference provides fine modulation to the load. The dual referenced switching amplifiers comprise the output filters made up of an inductor and a capacitor. In some embodiments, fine modulation is not applied to the load, thus limiting bipolar current flow induced by the filter inductors.09-01-2011
20130147552CLASS-D AMPLIFIER - A class-D amplifier includes a quantized amplifier, having no quantization error feedback circuit, coupled to receive a digital input signal, according to which an output signal is generated to be switched between power rails. The digital input signal is pre-compensated to correct an error. A low-pass filter is configured to operate on the output signal to generate a filtered output signal.06-13-2013
20130147551AMPLIFYING APPARATUS - There is provided an amplifying apparatus which can prevent characteristic deterioration while reducing costs. The amplifying apparatus includes a first amplifier connected between an input terminal to which a high-frequency signal is input and an output terminal through which the high-frequency signal is output, including a bipolar transistor, and amplifying the high-frequency signal input from the input terminal; a second amplifier including a bipolar transistor, amplifying the high-frequency signal input from the input terminal, and having a lower maximum output power than that of the first amplifier; and a switching unit connected between the second amplifier and the output terminal, and selectively outputting the high-frequency signal amplified by the second amplifier through the output terminal.06-13-2013
20090289709Closed loop timing feedback for PWM switching amplifiers using predictive feedback compensation - Methods and systems are disclosed for closed loop feedback for pulse width modulated (PWM) switching amplifiers using predictive feedback compensation (PFC) for suppressing distortions caused by supply voltage variations and output amplitude switching non-idealities in pulse width modulated (PWM) switching amplifiers by pre-compensating the PWM input based upon the supply voltage or output pulse amplitude and using closed loop timing feedback. Output amplitude errors associated with previous PWM output signals are used to predict output amplitude errors expected for future PWM output signals. These predicted output amplitude errors are then used to adjust the pulse widths for the future PWM output signals. Timing differences between pulse widths for the uncompensated PWM input signal and the pre-compensated PWM signal are used as feedback to provide closed loop width adjustment.11-26-2009
20100289579SWITCHABLE INPUT PAIR OPERATIONAL AMPLIFIERS - Techniques for designing a switchable amplifier are described. In one aspect, a switchable amplifier including a core amplifier circuit configured to selectively enable one or more parallel input transistor pairs is described. The core amplifier circuit comprises a permanently enabled input transistor pair. In another aspect, a device operable between a first mode of operation and a second mode of operation comprising a receiver logic circuit for selectably enabling and disabling a plurality of input transistor pairs within a switchable amplifier is described where the switchable amplifier also includes a core amplifier circuit coupled to the receiver logic circuit for selectably enabling and disabling a transistor pair therein. The described switchable amplifiers result in the ability to provide varying amplifier performance characteristics based upon the current mode of operation of the device.11-18-2010
20130154736Transient Signal Suppression for a Class-D Audio Amplifier Arrangement - A Class-D amplifier arrangement is disclosed that implements an auxiliary feedback loop and a primary feedback loop. The auxiliary feedback loop operates upon an input signal when the Class-D amplifier arrangement is operating under a power-up condition and a power-down condition so that a modulated signal is confined within the auxiliary feedback loop during the power-up condition and the power-down condition. The confinement of the modulated signal within the auxiliary feedback loop during the power-up condition and the power-down condition diverts transient signals coupled onto the modulated signal from an output device. The primary feedback loop operates upon the input signal when the Class-D amplifier arrangement is operating under a normal condition so that the modulated signal is introduced to the output device during the normal condition.06-20-2013
20130120063AMPLIFIER CIRCUIT - Class D amplifier circuits for amplifying an input signal. The amplifier has an H-bridge output stage and thus has switches for switchably connecting a first output to a first voltage, e.g. Vdd, or a second voltage (e.g. ground) and for switchably connecting a second output to the first or second voltages. A switch controller is configured to control the H-bridge stage so as to vary between a plurality of states including at least a first state in which the outputs are both connected to the first voltage and a second state in which the outputs are both connected to said second voltage. The switch controller is configured to vary the proportion of time spent in the first state relative to the second state based on an indication of the amplitude of the input signal. The amplifier may therefore have first circuitry for deriving a proportion value (α) based on the input signal (Din) and second circuitry for generating control signals for selecting the first state or said second state based on the proportion value (α).05-16-2013
20130187713POWER AMPLIFIER CIRCUIT AND CONTROL METHOD - A power amplifier circuit uses an output transistor and a cascode transistor. First and second drive circuits apply gate control signals to the two transistors, which rise and fall in synchronism, and this is such that the voltage drop across the cascode transistor is reduced (compared to a constant gate voltage being applied to the output transistor).07-25-2013
20120293257HIGH FREQUENCY POWER AMPLIFIER - A high frequency power amplifier includes: a first transistor for amplifying an input high-frequency signal; a second transistor for amplifying an output signal of the first transistor; a third transistor connected in parallel with the first transistor and for amplifying the input high-frequency signal; a first switching element connected between an output of the first transistor and an input of the second transistor; a second switching element connected between an output of the third transistor and the first switching element; third and fourth switching elements connected in series between the output of the first transistor and an output of the second transistor, and between the second switching element and the output of the second transistor; and a first capacitor connected between the third switching element and the fourth switching element.11-22-2012
20130200952POWER MOSFETS WITH IMPROVED EFFICIENCY FOR MULTI-CHANNEL CLASS D AUDIO AMPLIFIERS AND PACKAGING THEREFOR - A stereo class-D audio system includes a first die including four monolithically integrated NMOS high-side devices and a second a second die including four monolithically integrated PMOS low-side devices. The audio system also includes a set of electrical contacts for connecting the high and low-side devices to components within the a stereo class-D audio system, the set of electrical contacts including at least one supply contact for connecting the drains of the high-side devices to a supply voltage (Vcc) and at least one ground contact for connecting the drains of the low-side devices to ground, the electrical contacts also including respective contacts for each source of the high and low-side devices allowing the source of each high-side device to be connected to the source of a respective low-side device to form two H-bridge circuits.08-08-2013
20130093515PWM COMPARATOR AND CLASS D AMPLIFIER - The present disclosure generally relates to a PWM comparator and a class D. The PWM comparator described above introduces current feedback mechanism, basing the waveform state of received high frequency triangle signal and the level state of output signal of the PWM comparator, the hysteresis is changing dynamically. In the same resolution, the noise resistance ability of the PWM comparator described above is much better than that of the conventional PWM comparators which has a fixed hysteresis, thus the PWM comparator can work stably even if the duty cycle of output signal is nearly 100%.04-18-2013

Patent applications in class Including Class D amplifier