Patent application number | Description | Published |
20090009219 | Reducing Power Consumption In An Amplification Stage Driving A Sample And Hold Circuit While Maintaining Linearity - An input signal to be sampled by a sample and hold circuit is amplified separately by two amplifiers. The output of the first amplifier is provided to a boost circuit to maintain the impedance of a sampling switch contained in a signal dependent boost switch substantially constant. The output of the second amplifier is sampled via the sampling switch, and the sample is stored in a storage element. The second amplifier drives a reduced load, and may be implemented as a low bandwidth, low power amplifier to reduce overall power consumption. | 01-08-2009 |
20100102870 | WIDEBAND SWITCHED CURRENT SOURCE - A current source block provided according to an aspect of the present invention provides a substantially constant current even when the provision of the current is switched on and off at different frequencies. The current source block contains a main portion and a replica portion, with each portion having a current source and switches to connect output of the current source to corresponding output nodes. Additional connections are provided to enable the replica portion to counter deviations in the current output of the main portion due to parasitic effects. As a result, the current source block provides a constant current even when switched off/on at different (in particular high) frequencies. Such current source blocks may be used in components such as current steering DACs to obtain a linear response even at high operational frequencies. | 04-29-2010 |
20100127775 | AMPLIFIER FOR DRIVING EXTERNAL CAPACITIVE LOADS - An apparatus having a zero-pole that is dependant on an equivalent series resistance (ESR) and a load is provided. The apparatus comprises an amplifier stage that receives a first input voltage and a bias voltage, an intermediate stage that is coupled to the output node of the amplifier stage (where the intermediate stage outputs an intermediate voltage to an intermediate node), a first capacitor coupled between at least one of the internal transistors at an internal node and the intermediate node, a power transistor coupled between a second input voltage and the intermediate node, a second capacitor coupled between the internal node and the power transistor, and a feedback stage coupled to the intermediate node and to the amplifier stage. The amplifier stage also has an output node and includes a plurality of internal transistors. The second capacitor provides a third input voltage to the power transistor, and the ratio of the capacitance of the first capacitor to the capacitance of the second capacitor controls the position of the zero-pole. Additionally, the feedback stage is adapted to output an output voltage to a load, and wherein the feedback stage provides a feedback voltage to the amplifier stage. | 05-27-2010 |
20100133909 | SOFT-START CIRCUIT - An apparatus is provided. The apparatus comprises an input circuit, a startup circuit, and a current limiter. The input circuit is coupled to a first source and is adapted to provide a first voltage and a first current to a load having a capacitance. The startup circuit is coupled to the input circuit and to the first source, and the startup circuit includes a current source and a startup capacitor coupled in series with one another. The current limiter has a cascode circuit and a discharge circuit. The cascode circuit has a bias transistor and a power transistor coupled in series with one another to provide a second voltage and a second current to the load, where the bias transistor is coupled to a second source and where the bias transistor generally operates as source follower during startup. The discharge circuit is coupled to a node between the bias transistor and the power transistor of the cascode circuit and coupled to a node between the startup current source. | 06-03-2010 |
20110156670 | PASSIVE BOOTSTRAPPED CHARGE PUMP FOR NMOS POWER DEVICE BASED REGULATORS - A charge pump in a low dropout (LDO) regulator includes a first capacitor coupled to an output of an amplifier and to a gate of a pass transistor. A first plurality of switches is operable to couple a second capacitor between an output of the LDO regulator and to a ground in a first clock phase, such that the second capacitor charges to an output voltage. A second plurality of switches is operable to couple the second capacitor in parallel to the first capacitor in a second clock phase such that the second capacitor charges the first capacitor. | 06-30-2011 |
20110156671 | FAST LOAD TRANSIENT RESPONSE CIRCUIT FOR AN LDO REGULATOR - A fast load transient response circuit includes a feedback loop that senses a load transient; a first driver and a second driver responsive to a feedback signal from the feedback loop; and a first pass transistor and a second pass transistor with sources and drains being coupled to each other, and a gate of the first pass transistor being driven by the first driver and a gate of the second pass transistor being driven by the second driver. A width of the channel to length of the channel (W/L) ratio of the first pass transistor is different than that of the second pass transistor such that second pass transistor reacts faster than the first pass transistors to a load transient. | 06-30-2011 |
20110156686 | LDO REGULATOR WITH LOW QUIESCENT CURRENT AT LIGHT LOAD - A low dropout (LDO) regulator includes an amplifier having an input terminal, an output terminal; a first bias source and a second bias source, the first and second bias sources receiving a supply voltage, and a pass transistor and a sense transistor. Sources of the pass transistor and sense transistor are coupled to each other that receive the supply voltage. Gates of the pass transistor and sense transistor coupled to each other and to the output terminal of the amplifier. The LDO further includes a detection circuit responsive to a load current to deactivate the second bias source such that quiescent current in the amplifier is reduced. The detection circuit comprises a comparator coupled across a resistor. The resistor is coupled to a drain of the sense transistor. | 06-30-2011 |
20110234312 | AMPLIFIER WITH IMPROVED STABILITY - A circuit includes an amplifier that defines a positive input terminal, a negative input terminal, a positive output terminal and a negative output terminal. The circuit also includes a first positive feedback path between the positive input terminal and the positive output terminal of the amplifier. Further, the circuit includes a second positive feedback path between the negative input terminal and the negative output terminal of the amplifier. The first positive feedback path and the second positive feedback path compensate the amplifier. | 09-29-2011 |
20130069608 | VOLTAGE REGULATOR STABILIZATION FOR OPERATION WITH A WIDE RANGE OF OUTPUT CAPACITANCES - A voltage regulator includes a measurement circuit for obtaining a value representing a magnitude of an output capacitance connected at an output node of the voltage regulator. A correction circuit in the voltage regulator modifies a compensation circuit internal to the voltage regulator based on the value. The modification of the compensation circuit is done to ensure that sufficient stability margins to accommodate the output capacitance are ensured for the main feedback loop in the voltage regulator. In an embodiment, a voltage proportional to the output capacitance is detected at start-up of the voltage regulator, and a corresponding binary signal is generated. The logic value of the binary signal is used to add or remove components and/or circuit portions in the compensation circuit to ensure stability. The voltage regulator is thus designed to support a wide range of output capacitance values. | 03-21-2013 |
20130222052 | LINEAR VOLTAGE REGULATOR GENERATING SUB-REFERENCE OUTPUT VOLTAGES - A linear voltage regulator includes a pair of amplifiers. A first amplifier of the pair is used in conventional fashion to generate a regulated output voltage by controlling an impedance of a pass transistor in the linear voltage regulator, the controlling being based on a difference between a reference voltage and a voltage at a first node in a voltage divider network connected between the output terminal of the voltage regulator and a ground terminal. The second amplifier of the pair compares the regulated output voltage and a voltage at a second node in the voltage divider network, and injects a proportional current into the first node. Generation of a regulated output voltage lesser than the reference voltage is thereby enabled. | 08-29-2013 |