Abstract: An apparatus for a mobile communication device adapted for digital pre-distortion that includes a memory and a processor operatively coupled to the memory of the processor. The processor receives a first input signal and also receives a first output signal from a power amplifier that is based on the first input signal. The processor additionally varies compression applied to a second input signal based on the first output signal of the power amplifier, generates a distortion compensation vector for the second input signal based on the first output signal of the power amplifier, and also varies an input excitation signal supplied to the power amplifier based on the first output signal of the power amplifier.

Abstract: A wireless communication device can include an antenna configured to sense a radio frequency (RF) signal. The wireless communication device can include signal estimation circuitry configured to generate estimates of amplitude and frequency for unmodulated spurs within the RF signal. The wireless communication device can further include multi-tone generator circuitry coupled to the signal estimation circuitry and configured to generate a composite spur cancellation signal based on the estimates of amplitude and frequency for unmodulated spurs within the RF signal. The wireless communication device can further include adder circuitry configured to subtract the spur cancellation signal from the RF signal to generate a spur cancelled signal.

Abstract: A wireless communication device can include an antenna configured to sense a radio frequency (RF) signal. The wireless communication device can include signal estimation circuitry configured to generate estimates of amplitude and frequency for unmodulated spurs within the RF signal. The wireless communication device can further include multi-tone generator circuitry coupled to the signal estimation circuitry and configured to generate a composite spur cancellation signal based on the estimates of amplitude and frequency for unmodulated spurs within the RF signal. The wireless communication device can further include adder circuitry configured to subtract the spur cancellation signal from the RF signal to generate a spur cancelled signal.

Abstract: An apparatus for a mobile communication device adapted for digital pre-distortion that includes a memory and a processor operatively coupled to the memory of the processor. The processor receives a first input signal and also receives a first output signal from a power amplifier that is based on the first input signal. The processor additionally varies compression applied to a second input signal based on the first output signal of the power amplifier, generates a distortion compensation vector for the second input signal based on the first output signal of the power amplifier, and also varies an input excitation signal supplied to the power amplifier based on the first output signal of the power amplifier.

Abstract: Embodiments of a mobile communication device and method for digital pre-distortion (DPD) are disclosed herein. The mobile communication device may scale a sequence of input samples by per-sample scale factors to generate a sequence of output samples for input to a power amplifier (PA), the input samples scaled to compensate for distortion of the PA. The mobile communication device may generate the scale factors based on per-sample inner products between a common weight vector and a per-sample distortion compensation vectors. The mobile communication device may generate the distortion compensation vectors based on vector outputs of predetermined distortion compensation functions. The mobile communication device may update the common weight vector based on a distortion error sequence between the sequence of output samples and a sequence of feedback samples.

Abstract: A method of reducing a peak to average power ratio (PAR) of a signal may include generating an in-band error signal indicating in-band distortion of a compressed signal and generating an out-of-band error signal indicating out-of-band distortion of the compressed signal. The method may further include applying an in-band gain to the in-band error signal to generate an adjusted in-band error signal and applying an out-of-band gain to the out-of-band error signal to generate an adjusted out-of-band error signal. The method may also include combining the compressed signal with the adjusted in-band error signal and the adjusted out-of-band error signal to generate an output signal. The compressed signal may be combined with the adjusted error signals, and the in-band gain and the out-of-band gain may be based on the output signal such that distortion of the output signal is reduced with respect to distortion of the compressed signal.

Abstract: A method of reducing a peak to average power ratio (PAR) of a signal may include generating an in-band error signal indicating in-band distortion of a compressed signal and generating an out-of-band error signal indicating out-of-band distortion of the compressed signal. The method may further include applying an in-band gain to the in-band error signal to generate an adjusted in-band error signal and applying an out-of-band gain to the out-of-band error signal to generate an adjusted out-of-band error signal. The method may also include combining the compressed signal with the adjusted in-band error signal and the adjusted out-of-band error signal to generate an output signal. The compressed signal may be combined with the adjusted error signals, and the in-band gain and the out-of-band gain may be based on the output signal such that distortion of the output signal is reduced with respect to distortion of the compressed signal.

Abstract: A system for linearizing RF amplifiers employing baseband predistortion techniques provides additive or multiplicative predistortion of the quadrature (I/Q) input signal. The predistorter uses a discrete-time polynomial kernel to model the inverse transfer characteristic of the amplifier, providing separate and simultaneous compensation for nonlinear static distortion, linear dynamic distortion and nonlinear dynamic effects including reactive electrical memory effects. A predistortion controller monitors and compares the amplifier output with the quadrature input signal to compute estimates of the residual output distortion of the amplifier. Output distortion estimates are used to adaptively compute the predistorter parameter values in response to changes in the amplifier's operating conditions. The computed values are used in the predistorter.

Abstract: A system for digitally linearizing the nonlinear behaviour of RF high efficiency amplifiers employing baseband predistortion techniques is disclosed. The system provides additive or multiplicative predistortion of the digital quadrature (I/Q) input signal in order to minimize distortion at the output of the amplifier. The predistorter uses a discrete-time polynomial kernel to model the inverse transfer characteristic of the amplifier, providing separate and simultaneous compensation for nonlinear static distortion, linear dynamic distortion and nonlinear dynamic effects including reactive electrical memory effects. Compensation for higher order reactive and thermal memory effects is embedded in the nonlinear dynamic compensation operation of the predistorter in an IIR filter bank. The digital predistortion system of the invention may provide broadband linearization of highly nonlinear and highly efficient RF amplification circuits including, but not limited to, dynamic load modulation amplifiers.

Abstract: A system for digitally linearizing the nonlinear behaviour of RF high efficiency amplifiers employing baseband predistortion techniques is disclosed. The system provides additive or multiplicative predistortion of the digital quadrature (I/Q) input signal in order to minimize distortion at the output of the amplifier. The predistorter uses a discrete-time polynomial kernel to model the inverse transfer characteristic of the amplifier, providing separate and simultaneous compensation for nonlinear static distortion, linear dynamic distortion and nonlinear dynamic effects including reactive electrical memory effects. Compensation for higher order reactive and thermal memory effects is embedded in the nonlinear dynamic compensation operation of the predistorter in an IIR filter bank. A predistortion controller periodically monitors the output of the amplifier and compares it to the quadrature input signal to compute estimates of the residual output distortion of the amplifier.

Abstract: A system for digitally linearizing the nonlinear behaviour of RF high efficiency amplifiers employing baseband predistortion techniques is disclosed. The system provides additive or multiplicative predistortion of the digital quadrature (I/Q) input signal in order to minimize distortion at the output of the amplifier. The predistorter uses a discrete-time polynomial kernel to model the inverse transfer characteristic of the amplifier, providing separate and simultaneous compensation for nonlinear static distortion, linear dynamic distortion and nonlinear dynamic effects including reactive electrical memory effects. Compensation for thermal memory effects also is embedded in the nonlinear dynamic compensation operation of the predistorter and is implemented parametrically using an autoregressive dynamics tracking mechanism.

Abstract: A system for linearly transmitting an amplified output signal using predistortion is disclosed. The system uses a straight inverse modeling scheme with orthogonal predictor variables to more easily and accurately determine the inverse of the distortion caused by a power amplifier of a RF transmitter. The direct inverse modeling scheme of the present invention indexes the LUT using the modulated input signals instead of the potentially noisier output signals, which helps to increase the accuracy of the predistortion. The predistorter system stores complex coefficients in the LUT, which are then used as the tap weights of a non-linear digital filter implementing the predistorter. Finally, the trainer uses a modified version of the power amplifier output signal which results in better predistortion performance. The modified power amplifier output signal has the in-band distortion removed from the power amplifier output signal.

Abstract: A linear RF transmitter uses an adaptive forward model of the power amplifier in a feedforward linearization system. The forward model outputs a modeled power amplifier output signal, which is then used to calculate the error signal. The error signal represents the distortion caused by the power amplifier, which is then subtracted from the power amplifier output signal. The forward model can optionally model memory effects of the power amplifier transfer characteristic to more accurately generate the error signal. In addition, the forward model may be generated from the power amplifier output signals using orthogonal predictor variables to further improve performance. These orthogonal predictor values are then used to calculate parameter values used by a feedforward filter to model the power amplifier. A coordinate mapper then maps these calculated parameter values into a set of parameter values having the same coordinate system of the feedforward filter.

Abstract: A system for linearly transmitting an amplified output signal using predistortion whereby a straight inverse modeling scheme is used to more easily and accurately determine the inverse of the distortion caused by a power amplifier of a RF transmitter. The "inverse" of the power amplifier is directly modeled by considering the power amplifier as a signal processing block with the input and output ports reversed. As a result, the computationally intensive inversion required by conventional schemes is avoided. The predistorter system stores complex coefficients in a predistorter LUT, which are then used as the tap weights of a digital filter implementing the predistorter. The predistortion is done by a non-linear filter which incorporates both instantaneous and average envelope power or magnitude effects. The predistortion LUT is addressed as a function of the instantaneous envelope power or magnitude and past power or magnitude envelopes.