Patent application number | Description | Published |
20110080216 | Systems and Methods of Power Amplifier Digital Pre-Distortion - Systems and methods for power amplifier pre-distortion are provided. The systems and methods of power amplifier digital pre-distortion disclosed herein may include a generic pre-distorter architecture which can implement a variety of Volterra cross terms involving single dimension convolutions (first order dynamics). For hardware implementations, this generic pre-distorter is further fine-tuned to provide a choice between different sets of cross terms that can be selected for a given PA for optimal performance. The novel pre-distorter architecture provides flexibility to trade off memory depth for additional Volterra terms and vice versa. A further novelty is the ability to trade off both memory depth and cross terms for a higher sample rate operation, which may enable higher order non-linear pre-distortion, or support for higher signal bandwidths. A poly-phase non-linear filtering mode allows for this flexibility. | 04-07-2011 |
20110135034 | Digital Pre-Distortion of Non-Linear Systems with Reduced Bandwidth Feedback - Embodiments of the invention provide a DPD system where the transmit reference signal is transformed, including sub-sampling, frequency translation, and the like, to match the feedback signal, which goes thru a similar transformation process, to obtain an error signal. The same transformation is applied to a system model, which may be Jacobian, Hessian, Gradient, or the like, in an adaptation algorithm to minimize error. | 06-09-2011 |
20110317786 | System and Method for Estimating a Transmit Channel Response and/or a Feedback Channel Response Using Frequency Shifting - Systems and methods for identifying a transmission channel response and a feedback channel response from a plurality of composite system responses are disclosed. A plurality of shifted feedback signals are created by shifting a feedback signal frequency by a plurality of first offset values and/or by shifting a transmission signal frequency by a plurality of second offset values. The feedback signals are compared to an input signal to identify the transmission channel response and/or a feedback channel response. A control signal is generated for a pre-distortion circuit to modify the input signal by an inverse of the transmission channel response. The composite system response is measured at a plurality of operating frequencies and at the plurality of offset values. The measurements are stored in a matrix and singular value decomposition is applied to the matrix of measurements to calculate the transmission channel response and feedback channel response. | 12-29-2011 |
20120069931 | MULTI-BAND POWER AMPLIFIER DIGITAL PREDISTORTION SYSTEM AND METHOD - Traditionally, for multi-band communication systems, independent signal chains for each of the different bands are employed. By using such an architecture, there are a large number of components, and there is substantial power consumption. Here, transmit processor is provided that enables transmission across multiple bands using few components (namely, fewer signal chains), while also provided for digital predistortion. | 03-22-2012 |
20120250790 | FREQUENCY SELECTIVE IQ CORRECTION - In conventional radio frequency (RF) systems, transmitters will usually convert baseband signals to RF so as to be transmitted. As part of the conversion process, the transmitters will perform digital preditortion (DPD), which uses feedback from a power amplifier. However, there are usually mismatches between the in-phase (I) and quadrature (Q) paths within with feedback loop. Traditional IQ correction filters were ineffective at providing adequate compensation for these mismatches, but here a filter is provided that provides adequate out-of-band compensation by use of frequency selectivity. | 10-04-2012 |
20120286863 | APPARATUS AND METHOD OF DIGITAL PREDISTORTION FOR POWER AMPLIFIERS WITH DYNAMIC NONLINEARITIES - Power amplifiers (PAs) using a Doherty or other power output level sensitive configuration have been employed for several years in telecommunications (as well as other applications) to take advantage of efficiency gains. For many of these applications, baseband signals are predistorted to compensate for nonlinearities in the PAs, but because there is a “switching event” in a Doherty-type amplifier (for example), the nonlinearities become dynamically varying. As a result, digital predistortion (DPD) becomes increasingly difficult to perform. Here, DPD modules are provided that adapt to changes in dynamically varying PAs based on a determination of the average power or other relevant metric prior to transmission. | 11-15-2012 |
20120286868 | CLASS 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 |
20130147533 | PHASE AVERAGED PULSE WIDTH MODULATOR - A method is provided. A noise shaped signal having a plurality of instants is generated with each instant being associated with at least one of a plurality of output levels. A next phase is selected for each instant, where each next phase is a circularly shifted phase based at least in part on a previous phase for the associated output level for its instant. A plurality of PWM signals is then generated using the phase for each instant, and an amplified signal is generated from the plurality of PWM signals. | 06-13-2013 |
20130148760 | TRANSFORMER POWER COMBINER WITH FILTER RESPONSE - A method for generating an amplified radio frequency (RF) signal is provided. In-phase (I) and quadrature (Q) signals are received and interleaved so as to generate a time-interleaved signal. Delayed time-interleaved signals are then generated from the time interleaved signal, and each of the delayed time-interleaved signals is amplified so as to generate a plurality of amplified signals. The amplified signals are then combined with a transformer, where the delayed time-interleaved signals are arranged to generate a filter response with the transformer. | 06-13-2013 |
20130156089 | DIGITAL TIME-INTERLEAVED RF-PWM TRANSMITTER - A method for transmitting radio frequency (RF) signals is provided. In-phase (I) and quadrature (Q) signals are received and filtered using sigma-delta modulation. I and Q pulse width modulation signals are generated from the filtered I and Q signals and interleaved so as to generate a time-interleaved signal. The time-interleaved signal is then amplified to generate the RF signals. | 06-20-2013 |
20130210376 | LINC TRANSMITTER WITH IMPROVED EFFICIENCY - A radio frequency (RF) transmitter is provided. The RF transmitter includes first and second drivers that are configured to receive first and second sets of complementary RF signals. Restoration circuits are coupled to the first and second drivers, and a bridge circuit is coupled to the first and second restoration circuits. By having the restoration circuits and the bridge circuit, a common mode impedance and a differential impedance can be provided, where the common mode impedance is lower than the differential impedance. | 08-15-2013 |
20130234795 | FREE-FLY CLASS D POWER AMPLIFIER - A method is provided. A first enable signal is asserted so as to enable a first driver, where the first driver has a first output and a first parasitic capacitance. A second enable signal is asserted so as to enable a second driver, where the second driver has a second output and a second parasitic capacitance. The first and second outputs are coupled together by a switching network when the second driver is enabled. Pulses from complementary first and second radio frequency (RF) signals are applied to the first driver, where there is a first set of free-fly intervals between consecutive pulses from the first and second RF signals, and pulses from complementary third and fourth RF signals are applied to the second driver, wherein there is a second set of free-fly interval between consecutive pulses from the third and fourth RF signals. | 09-12-2013 |
20130241663 | PULSE WIDTH MODULATION SCHEME WITH REDUCED HARMONICS AND SIGNAL IMAGES - A method is provided. An input signal is received, and a noise-shaped signal is generated from the input signal. The noise-shaped signal is formed from a plurality of noise-shaping levels. A pulse stream is generated from the noise-shaped signal over a plurality of periods, where each period has a plurality of frames. The pulse stream also includes a plurality of pulse sets, where each pulse set is associated with at least one of the noise-shaping levels, and, for each pulse set having a total pulse width for its period that is less than its period and greater than zero, each pulse set includes at least one pulse in each frame for its period. | 09-19-2013 |
20140133602 | Digital Pre-Distortion of Non-Linear Systems with Reduced Bandwidth Feedback - Embodiments of the invention provide a DPD system where the transmit reference signal is transformed, including sub-sampling, frequency translation, and the like, to match the feedback signal, which goes thru a similar transformation process, to obtain an error signal. The same transformation is applied to a system model, which may be Jacobian, Hessian, Gradient, or the like, in an adaptation algorithm to minimize error. | 05-15-2014 |
20140169496 | Crest Factor Reduction for Multi-Band System - Systems and methods for crest factor reduction (CFR) are described. A multi-band CFR architecture achieves significant hardware savings without sacrificing CFR performance by applying peak cancellation to each band individually. However, peak detection is calculated based on a combined input signal. | 06-19-2014 |
20150030099 | CIRCUITS AND METHODS FOR REDUCING THE AMPLITUDE OF COMPLEX SIGNALS - For crest factor reduction in a first signal having first and second components, the first component is delayed. A second signal is generated in response to detecting that a peak in the first component exceeds a predetermined threshold. Amplitude of the peak in the first component is reduced in response to detecting that the peak in the first component exceeds the predetermined threshold. Reducing amplitude of the peak in the first component includes adding the second signal to the delayed first component. | 01-29-2015 |
20150070088 | Circuits And Methods For Cancelling Nonlinear Distortions In Pulse Width Modulated Sequences - A method of canceling nonlinear distortions in pulse width modulated signals includes receiving an input signal. A first signal that is the modulated input signal is generated. The first signal has quantized levels representing the input signal. A pulse width modulated (PWM) sequence that is representative of the first signal is generated. A second signal that is the PWM sequence mixed with a carrier signal is generated. An error signal is generated in response to the first signal and modeled from the second signal. The error signal is added to the input signal. | 03-12-2015 |