Abstract: A method and system for pre-distorting a dual band signal to compensate for distortion of a non-linear power amplifier in a radio transmitter are disclosed. In one embodiment, a first and second signal of the dual band signal are up-sampled at a sampling rate that is based at least in part on the bandwidth of at least one of the first and second signals and based at least in part on an intermediate frequency by which the first and second signal are tuned before pre-distortion of the tuned signals.

Abstract: Systems and methods for compensating for non-linearity of a non-linear subsystem using predistortion are disclosed. In one embodiment, a system includes a non-linear subsystem and a predistorter configured to effect predistortion of an input signal of the non-linear subsystem such that the predistortion compensates for a non-linear characteristic of the non-linear subsystem. The system also includes an adaptor that adaptively configures the predistorter based on a feedback signal that is representative of an output signal of the non-linear subsystem and an input signal that is representative of the input signal of the non-linear subsystem. The adaptor generally models the non-linear subsystem as a concatenation of a non-linear model that corresponds to the non-linear characteristic of the non-linear subsystem and a linear model that corresponds to a known linear characteristic of the non-linear subsystem.

Abstract: A method and system for modeling distortion of a non-linear electronic device are disclosed. According to one aspect, the invention provides a layered memory structure that includes a plurality of memory structure layers. Each memory structure layer has an input to receive an input signal and has a memory function. Each memory function has at least one delay element that provides a pre-determined delay of the input signal of the memory structure layer. The pre-determined delay is different for each of at least two memory structure layers and is based at least in part on an evaluation period corresponding to the memory structure layer.

Abstract: One or more embodiments of a method and apparatus taught herein provide a predistortion system to compensate for the non-linearity of a power amplifier. The system includes an outer predistorter, an inner predistorter, and a first adaptation circuit. The predistorter predistorts an input signal to generate a first output signal, and uses a first memory model that models power amplifier memory effects within a first range of time constants. The inner predistorter predistorts the first output signal to generate a second output signal, and uses a second memory model that models power amplifier memory effects within a second range of time constants that is greater than the first range of time constants. The second output signal is provided as an input to the power amplifier, and the first adaptation circuit adapts the outer predistorter responsive to feedback from the power amplifier.

Abstract: The present disclosure relates to an undersampling observation receiver for use in a power amplifier digital predistortion system for concurrent multi-band signals. In one embodiment, an undersampling observation receiver receives a concurrent multi-band signal output by a power amplifier. The concurrent multi-band output signal includes multiple original frequency bands. The undersampling observation receiver undersamples the concurrent multi-band signal at a select sampling rate to provide an undersampled multi-band signal. The select sampling rate is such that a frequency-flipped image of at least one of the original frequency bands and images of any remaining original frequency bands fall within a frequency range of zero to half of the select sampling rate and do not overlap one another.

Abstract: Disclosed is a signal splitting apparatus useable in a power amplifier having two or more power amplifiers. The apparatus includes a direct gain component; and a derived gain component connected to the direct gain component. The derived gain component derives the derived gain from the direct gain by imposing a constraint which is valid over the entire dynamic range of the input signal, e.g. the sum of the power of the direct split signal and the derived split signal are constrained to be substantially equal to the power of the input signal. The use of combining additional direct gain and derived gain components, as well as a delay element, are disclosed so as to enable n-component splitting that for adaptation to different applications by the use of suitable coefficients.

Abstract: A method and system for pre-distorting a dual band signal to compensate for distortion of a non-linear power amplifier in a radio transmitter are disclosed. In one embodiment, the first signal of the dual band signal is tuned to a first intermediate frequency to produce a first tuned signal and the second signal of the dual band signal is tuned to minus the intermediate frequency to produce a second tuned signal. A single input pre-distorter pre-distorts the sum of the first tuned signal and the second tuned signal. The coefficients of the pre-distorter are obtained from a one-dimensional look-up table.

Abstract: Embodiments include a method for predistorting an input signal at a predistorter to compensate for distortion introduced by a non-linear electronic device operating on the input signal to produce an output signal. The method entails generating first and second signal samples for each of a plurality of sampling time instances. The first and second signal samples represent the input and output signals, and are spaced at unit-delay intervals. The method further entails calculating, from the first and second signal samples, parameters for an ANN-based model. The ANN-based model includes a tapped delay line configured to dynamically model memory effects of the distortion introduced by the device, or of the response of the predistorter, with a multi-unit delay interval between at least one pair of adjacent delays. The method also includes predistorting the input signal according to the ANN-based model, to produce a predistorted input signal for input to the device.

Abstract: A predistorter applies a distortion function to an input signal to predistort the input signal. The output of the distortion function is modeled as the sum of the output signals from the orthogonal basis functions weighted by corresponding weighting coefficients. Techniques are described for orthogonalizing the basis function output signals depending on the distribution of the input signal.

Abstract: Methods and apparatus are disclosed for predistorting an input signal to compensate for non-linear distortions introduced by an electronic device, for example, a power amplifier. The non-linear effects of a power amplifier can be modeled using different behavior models. Coefficients for one behavior model can be converted into coefficients for a different behavior model using a conversion function. A conversion circuit implementing the conversion function can be used in between a predistorter and an adaptation circuit that use different models.

Abstract: A method and system for pre-distorting a dual band signal to compensate for distortion of a non-linear power amplifier in a radio transmitter are disclosed. In one embodiment, a first and second signal of the dual band signal are up-sampled at a sampling rate that is based at least in part on the bandwidth of at least one of the first and second signals and based at least in part on an intermediate frequency by which the first and second signal are tuned before pre-distortion of the tuned signals.

Abstract: Digital predistorter circuits with selectable basis function configurations are described. In some embodiments, an input scaling block is introduced prior to a basis function generator structure. The input scaling factor is based on the input signal's average power. In other embodiments, configurable connection coefficients are used to construct the orthogonal basis functions. Multiple sets of tap weights for the predistorter are maintained, each set corresponding to a given basis function configuration. In an example method for pre-distorting an input signal to compensate for distortion introduced by an electronic device, a statistic characterizing the input signal is calculated, and one of a pre-determined set of basis function configurations is selected, based on the statistic.

Abstract: The present invention provides a method an apparatus for predistorting an input signal to compensate for non-linearities in an electronic device that operates on the input signal. The invention may be used, for example, to digitally predistort an input signal for a power amplifier in a wireless communication device. The predistorter uses a polynomial approach based on the well-known Volterra series to model the distortion function. A dynamic deviation reduction technique is used to reduce the number of terms in the distortion model and to facilitate implementation. The approach described herein eliminates square functions present in prior art designs and can be implemented using CORDIC circuits.

Abstract: The present invention provides a method an apparatus for predistorting an input signal to compensate for non-linearities in an electronic device that operates on the input signal. The invention may be used, for example, to digitally predistort an input signal for a power amplifier in a wireless communication device. The predistorter uses a polynomial approach based on the well-known Volterra series to model the distortion function. A dynamic deviation reduction technique is used to reduce the number of terms in the distortion model and to facilitate implementation. The approach described herein eliminates square functions present in prior art designs and can be implemented using CORDIC circuits.

Abstract: A method and apparatus for memory modeling in a pre-distortion architecture are disclosed. In one embodiment, a memory model has a plurality of branches. Each branch receives a different output basis function signal. Each branch includes at least one delay element. Each delay element causes a pre-determined delay of the output basis function signal received by the branch. The amount of a pre-determined delay is different for each of at least two branches.

Abstract: A method and apparatus for modeling distortion of a non-linear device are disclosed. A pre-distorter model has a plurality of branches. Each branch receives a different output basis function signal. At least one branch includes a down-sampler, a memory structure and an up-sampler. The down-sampler down-samples the received output basis function signal received by the branch by a factor of 1/Mk, where Mk is different for each of the at least one branches. The memory structure includes at least one delay element to delay the output of the down-sampler according to a predetermined delay. The memory structure has an output based on an output of the at least one delay element. The up-sampler up-samples the output of the memory structure by the up-sampling factor, Mk.

Abstract: Methods and apparatus are disclosed for compressing and decompressing data to reduce bandwidth requirements in transmissions of predistorted signals between a processing node and a remote transmitting node of a power amplifier with digital predistortion (PA-DPD) system. In the processing node, predistorted signals are decomposed into a high-dynamic range signal of a first sample rate and a low-dynamic range signal of a second sample rate greater than the first sample rate. Samples of both signals are combined to generate a compressed signal for transmission to the remote transmitting node, which decompresses the compressed signal to restore the predistorted signal.

Abstract: One or more embodiments of a method and apparatus taught herein provide a predistortion system to compensate for the non-linearity of a power amplifier. The system includes an outer predistorter, an inner predistorter, and a first adaptation circuit. The predistorter predistorts an input signal to generate a first output signal, and uses a first memory model that models power amplifier memory effects within a first range of time constants. The inner predistorter predistorts the first output signal to generate a second output signal, and uses a second memory model that models power amplifier memory effects within a second range of time constants that is greater than the first range of time constants. The second output signal is provided as an input to the power amplifier, and the first adaptation circuit adapts the outer predistorter responsive to feedback from the power amplifier.

Abstract: A method and system for modeling distortion of a non-linear electronic device are disclosed. According to one aspect, the invention provides a layered memory structure that includes a plurality of memory structure layers. Each memory structure layer has an input to receive an input signal and has a memory function. Each memory function has at least one delay element that provides a pre-determined delay of the input signal of the memory structure layer. The pre-determined delay is different for each of at least two memory structure layers and is based at least in part on an evaluation period corresponding to the memory structure layer.

Abstract: A method and system for pre-distorting a dual band signal to compensate for distortion of a non-linear power amplifier in a radio transmitter are disclosed. In one embodiment, the first signal of the dual band signal is tuned to a first intermediate frequency to produce a first tuned signal and the second signal of the dual band signal is tuned to minus the intermediate frequency to produce a second tuned signal. A single input pre-distorter pre-distorts the sum of the first tuned signal and the second tuned signal. The coefficients of the pre-distorter are obtained from a one-dimensional look-up table.