Class / Patent application number | Description | Number of patent applications / Date published |
455302000 | Image frequency suppression | 19 |
20090098847 | APPARATUS FOR EXTENDING THE BANDWIDTH OF A SPECTRUM ANALYZER - A spectrum analyzer is provided with frequency-scalable circuit architectures that extend the bandwidth of the spectrum analyzer using an array of couplers. The array of couplers is distributed along the RF signal path at one end, and interfaced to one or more frequency-translation devices such as mixers or samplers at the other. In a first architecture, a single mixer is employed with an LO signal applied to one input and coupler outputs providing RF signals to another input, with switching controlled to select one coupler's RF output to provide to the mixer. In a second architecture, a separate mixer is used, one for each coupler RF signal, with switches selecting one of the mixer IF outputs to select a desired output frequency. Both the first and second embodiments eliminate switching and its associated loss and frequency limitations from the main RF signal path to enable wideband high-dynamic-range spectrum analysis. | 04-16-2009 |
20090203342 | FAST IMAGE REJECTION - Fast image rejection. Dual down conversion processing of a received signal by performing both low side injection and high side injection thereby generating a first down converted signal and a second down converted signal. Analysis of one or both of the first and second down converted signals, including the signal and image components thereof, is performed to determine which of the first down converted signal and the second down converted signal is appropriate to be selected for subsequent baseband processing. For example, if a signal strength of an image within the first down converted signal is less than a signal strength of a signal component within the first down converted signal, then the first down converted signal is most likely the appropriate signal to undergo baseband processing. Alternatively, if the converse is true, then the second down converted signal may be the appropriate signal to undergo baseband processing. | 08-13-2009 |
20090258628 | Time-Error and Frequency-Error Correction in a Multi-Carrier Wireless Communications System - Methods and apparatus for automatic frequency control in wireless receivers configured to simultaneously receive multiple carrier signals at distinct radio frequencies are disclosed. An exemplary wireless device comprises at least first and second radio front-end circuits configured to receive first and second wireless communication signals transmitted via first and second radio-frequency carriers at distinct first and second radio frequencies, respectively, a control processor configured to designate a master carrier signal and a slave carrier signal from among the received wireless communication signals, and a frequency error estimation circuit configured to estimate a first receiver frequency error using the received master carrier signal. The control processor is further configured to calculate a second receiver frequency error from the first receiver frequency error, for use in compensating one or more receiver processes performed on the slave carrier signal. | 10-15-2009 |
20100015939 | PROGRAMMABLE IF FREQUENCY FILTER FOR ENABLING A COMPROMISE BETWEEN DC OFFSET REJECTION AND IMAGE REJECTION - A center frequency of an adjustable filter is controlled to achieve a compromise between DC offset rejection and image rejection. | 01-21-2010 |
20100159866 | Systems and methods for interference cancellation - Systems and methods for interference cancellation in which a first signal having a first frequency may be cancelled with a second frequency having a second and different (e.g., lower) frequency by employing sampling to cancel the first signal with the separate signal at the sample instances. | 06-24-2010 |
20100167680 | Controllable image cancellation in a radio receiver - In one embodiment, a receiver includes parallel paths for signal channel processing and image channel processing. The paths may include a mixer to receive an intermediate frequency (IF) signal and to downconvert the IF signal to a channel baseband signal, a filter to generate a filtered channel value, a combiner to combine the channel baseband signal with a filtered channel value from the other path to obtain a channel path output, in addition to one or more controllers to generate a step control signal and update a weighting of the filters based at least in part on the step control signal. | 07-01-2010 |
20100227580 | CIRCUIT AND METHOD FOR IMAGE FREQUENCY REJECTION - A circuit and method for image frequency rejection is provided that includes an analog dual-quadrature mixer device whose signal inputs for an in-phase-signal and a quadrature-phase signal are connected to an input circuit in the signal path and whose oscillator inputs for an in-phase oscillator signal and a quadrature-phase oscillator signal are connected to a local oscillator device, having an analog adder-amplifier device, which has a number of transistor pairs, in which in each case both transistors of each transistor pair are connected to the same load resistor for the addition of the signals applied at the control inputs of both transistors, and in which the control inputs of both transistors are connected downstream of the outputs of analog dual-quadrature mixer device, and having a multistage analog polyphase filter whose inputs are connected to outputs of the adder-amplifier device. | 09-09-2010 |
20100330947 | Providing Image Rejection Calibration For A Receiver - According to one embodiment, a method for updating filter values of an image canceller is provided. The method may include determining a channel-to-image (C/I) ratio between a channel signal and an image signal at the canceller input and generating a gain control value based at least in part on the C/I ratio. Then correlations between the channel signal and the image signal at the canceller's input and output can be generated, along with a gear control value based at least in part on a ratio between the correlations. In turn, one or more filters of the canceller can be updated using the control values. | 12-30-2010 |
20110009081 | METHOD OF OPERATION OF A PASSIVE HIGH-FREQUENCY IMAGE REJECT MIXER - A passive implementation of an image reject mixer (IRM), capable of operating at very high frequency, is operative according to the disclosed method. The IRM comprises a quad MOS multiplier and a lumped-element hybrid, resulting in a passive IRM. Operative at a radio frequency (RF) of tens of GHz with an intermediate frequency (IF) of several GHz. The RF+ and RF− signals are provided to two quad MOS multipliers. A local oscillator signal (LO) is used to provide LO+ and LO− signals to one of the multipliers and by providing the LO to a phase shifter, generated are a ninety degree shifted LO+ and LO− signals provided to the other multiplier. Providing the hybrids with the outputs of both multipliers and selecting an appropriate IF signal from each of the hybrids ensures the proper operation of the passive IRM. | 01-13-2011 |
20110070858 | IMAGE REJECTION - A receiver ( | 03-24-2011 |
20110086605 | IMAGE CALIBRATION AND CORRECTION FOR LOW-IF RECEIVERS - Embodiments of a system for calibrating the image rejection of a receiver include an image-rejection correction circuit that modifies the gain and phase of a first channel of a baseband image signal. The image-rejection correction circuit may include a summing circuit and first and second variable-gain elements. In one implementation, a filter receives a corrected first channel from the image-rejection correction circuit and an unmodified second channel of the image signal, while a controller analyzes power measured at the output of the filter, and adjusts the variable-gain elements to reduce the power of the image signal. | 04-14-2011 |
20110105071 | IMAGE FREQUENCY REJECTION MIXER - An image frequency rejection mixer has a first differential transconductor that receives a differential mixer input signal, a second differential transconductor that receives the differential mixer input signal and cross-coupled to the first differential transconductor, a first mixing circuit that generates a first differential mixing circuit output signal by mixing a first differential information signal with a first local oscillation signal, a second mixing circuit that generates a second differential mixing circuit output signal by mixing a second differential information signal with a second local oscillation signal, with the first local oscillation signal and the second local oscillation signal being in quadrature, and an image rejection circuit that generates a differential mixer output signal from the first and second differential mixing circuit output signals. | 05-05-2011 |
20110136460 | MIXER AND RADIO FREQUENCY RECEIVER USING THE MIXER - A mixer used in a Radio Frequency (RF) receiver is provided. The mixer includes a first harmonic rejecter for rejecting a harmonic signal component from a first input signal; and a second harmonic rejecter for rejecting a harmonic signal component from a second input signal. The first harmonic rejecter and the second harmonic rejecter are connected in parallel to reject an image signal component from the first input signal and the second input signal. Thus, the RF receiver can reject the harmonic signal and the image signal without using an external element. | 06-09-2011 |
20110189970 | Receiving apparatus and image rejection method - An orthogonal mixer generates first I and Q signals by down-converting an RF signal. A complex filter has an asymmetrical frequency gain property between a positive frequency domain and a negative frequency domain, and generates second I and Q signals by suppressing image signals included in the first I and Q signals compared with desired signals. An orthogonal compensation circuit is located at a subsequent stage of the complex filter, and corrects the second I and Q signals to cancel a phase difference error and an amplitude error of the desired signals between the second I and Q signals. Further, a control circuit adjusts an element characteristic of the complex filter to cancel a phase difference error and an amplitude error of the image signals that appear in the second I and Q signals. | 08-04-2011 |
20120322398 | Harmonic Rejection Mixer Architecture with Reduced Sensitivity to Gain and Phase Mismatches - A harmonic rejection mixer includes a first scaling circuit for scaling an RF signal to generate a plurality of scaled RF signals, a first switching stage for sampling the scaled RF signals using a first plurality of switching signals, and a second mixing stage for mixing the sampled RF signals with a second plurality of switching signals to generate a plurality of frequency translated signals having different phases. A combiner adds the frequency translated signals together to generate a first plurality of baseband versions of the RF signal. A first amplifier stage processes the first plurality of baseband versions to generate a second plurality of baseband versions. The mixer further includes a second scaling circuit for scaling the second plurality of baseband versions and a second amplifier stage to generate an in-phase baseband signal and a quadrature baseband signal from the scaled second plurality of baseband versions. | 12-20-2012 |
20130023226 | IMAGE CANCELLATION IN RECEIVERS USING DUAL ADAPTIVE FILTERS - The present disclosure includes apparatus, systems, and techniques relating to receiver image cancellation. A described technique includes receiving a downconverted signal in a digital domain, the downconverted signal including an in-phase signal and a quadrature signal; generating a first signal of a signal channel based on the downconverted signal; generating a second signal of an image channel based on the downconverted signal; filtering the second signal using first weights to produce a pilot training signal; filtering the second signal using second weights to produce an image cancellation signal; generating an output signal by subtracting the image cancellation signal from the first signal to resolve the desired signal; updating the first weights based on the first weights, the second signal, the pilot training signal, and a pilot signal; and updating the second weights based on the second weights, the output signal, and the pilot training signal. | 01-24-2013 |
20140242935 | Wide-Bandwidth Signal Canceller - A signal canceller includes a dual-drive electro-optic modulator having separate first and second electrical inputs. The first electrical input is coupled to a first portion of a first signal and the second electrical input is coupled to a second signal and to a second portion of the first signal. A laser generates an optical beam that propagates from the optical input to an optical output of the electro-optic modulator. The dual-drive electro-optic modulator modulates the optical beam with the first and second portions of the first signal and with the second signal. The modulation cancels at least some the first signal and generates a modulation signal with reduced first signal modulation component. | 08-28-2014 |
20140342684 | Method of Manufacture of a Passive High-Frequency Image Reject Mixer - A passive implementation of an image reject mixer (IRM), capable of operating at very high frequency, is manufactured in a variety of silicon processes. The IRM comprises a quad MOS multiplier and a lumped-element hybrid, resulting in a passive IRM, operative at radio frequencies (RF) of tens of GHz with an intermediate frequency (IF) of several GHz. The RF+ and RF− signals are provided to two quad MOS multipliers. A local oscillator signal (LO) is used to provide LO+ and LO− signals to one of the multipliers and by providing the LO to a phase shifter, generated are a ninety degree shifted LO+ and LO− signals provided to the other multiplier. Providing the hybrids with the outputs of both multipliers and selecting an appropriate IF signal from each of the hybrids ensures the proper operation of the passive IRM. | 11-20-2014 |
20150349900 | WIDEBAND CALIBRATION METHOD AND WIDEBAND CALIBRATION APPARATUS FOR CALIBRATING MISMATCH BETWEEN FIRST SIGNAL PATH AND SECOND SIGNAL PATH OF TRANSMITTER/RECEIVER - A method for calibrating mismatches of an in-phase signal path and a quadrature signal path of a transmitter, including: utilizing the receiver to receive at least a test signal via the first signal path and the second signal path, wherein each test signal possesses a specific frequency within a specific frequency band; calculating at least a calibration coefficient for each test signal respectively, so as to calibrate mismatch between the first signal path and the second signal path of the receiver with respect to the specific frequency corresponding to each test signal; deriving a tap coefficient of a calibration filter of a calibration filter unit according to the at least a calibration coefficient of each test signal; and utilizing the calibration filter unit to calibrate a received signal. | 12-03-2015 |