Abstract: Apparatus and methods provide predistortion for a phased array. Radio frequency (RF) sample signals from phased array elements are provided along return paths and are combined by a hardware RF combiner. Phase shifters are adjusted such that the RF sample signals are phase-aligned when combined. Adaptive adjustment of predistortion for the amplifiers of the phased array can be based on a signal derived from the combined RF sample signals.

Abstract: Various examples are directed to systems and methods for operating a plurality of power amplifiers. A predistortion circuit may pre-distort an input signal according to a predistortion configuration to generate a pre-distorted signal for the plurality of power amplifiers. An adaption circuit may receive a first feedback signal from a first power amplifier of the plurality of power amplifiers and generate predistortion correlation data describing a correlation between parameters of a model describing the plurality of power amplifiers. The adaption circuit may receive a first feedback signal from a second power amplifier of the plurality of power amplifiers and update the predistortion correlation data to generate updated predistortion correlation data using the first feedback signal from the second power amplifier. The adaption circuit may also generate the predistortion configuration using the updated predistortion correlation data.

Abstract: Apparatus and methods provide predistortion for a phased array. Radio frequency (RF) sample signals from phased array elements are provided along return paths and are combined by a hardware RF combiner. Phase shifters are adjusted such that the RF sample signals are phase-aligned when combined. Adaptive adjustment of predistortion for the amplifiers of the phased array can be based on a signal derived from the combined RF sample signals.

Abstract: Various examples are directed to systems and methods for operating a plurality of power amplifiers. A predistortion circuit may pre-distort an input signal according to a predistortion configuration to generate a pre-distorted signal for the plurality of power amplifiers. An adaption circuit may receive a first feedback signal from a first power amplifier of the plurality of power amplifiers and generate predistortion correlation data describing a correlation between parameters of a model describing the plurality of power amplifiers. The adaption circuit may receive a first feedback signal from a second power amplifier of the plurality of power amplifiers and update the predistortion correlation data to generate updated predistortion correlation data using the first feedback signal from the second power amplifier. The adaption circuit may also generate the predistortion configuration using the updated predistortion correlation data.

Abstract: Apparatus and methods provide predistortion for a phased array. Radio frequency (RF) sample signals from phased array elements are provided along return paths and are combined by a hardware RF combiner. Phase shifters are adjusted such that the RF sample signals are phase-aligned when combined. Adaptive adjustment of predistortion for the amplifiers of the phased array can be based on a signal derived from the combined RF sample signals.

Abstract: An apparatus that implements DPD in a manner that can address OOB instability issues, PE instability issues, or both, is disclosed. The apparatus includes an actuator circuit configured to use a model of a power amplifier (PA) to apply a predistortion to at least a portion of an input signal, and an error correction circuit configured to generate an error signal indicative of a deviation of the output of the actuator circuit from the target output, e.g., in terms of OOB or PE. The apparatus also includes an adaptation circuit configured to update the model based on the error signal. By using such an error in adapting the model used for the DPD, undesirable effects of performing DPD, such as creation or amplification of OOB frequency components, or increasing amplitude of some samples, may be reduced or eliminated.

Abstract: Various examples are directed to systems and methods for operating a plurality of power amplifiers. A predistortion circuit may pre-distort an input signal according to a predistortion configuration to generate a pre-distorted signal for the plurality of power amplifiers. An adaption circuit may receive a first feedback signal from a first power amplifier of the plurality of power amplifiers and generate predistortion correlation data describing a correlation between parameters of a model describing the plurality of power amplifiers. The adaption circuit may receive a first feedback signal from a second power amplifier of the plurality of power amplifiers and update the predistortion correlation data to generate updated predistortion correlation data using the first feedback signal from the second power amplifier. The adaption circuit may also generate the predistortion configuration using the updated predistortion correlation data.

Abstract: An example apparatus includes a power amplifier (PA) and a linearity optimizer. The optimizer includes a PA actuator and a linearity adaptation circuit. The actuator is configured to generate an actuator output based on an actuator input and a vector of complex gains computed by the linearity adaptation circuit based on a feedback signal indicative of PA's output. The adaptation circuit is configured to compute the vector of complex gains in a manner that maximizes the power of the actuator output while ensuring that the deviation of PA's behavior from a linear behavior (e.g., in terms of one or more linearity parameters) is below a threshold. Controlling actuator output in a manner that maximizes its power while taking into consideration one or more linearity parameters to ensure that target linearity is achieved controls drive signals for the PA and, thus, may help in terms of PA linearity and efficiency.

Abstract: Apparatus and methods provide predistortion for a phased array. Radio frequency (RF) sample signals from phased array elements are provided along return paths and are combined by a hardware RF combiner. Phase shifters are adjusted such that the RF sample signals are phase-aligned when combined. Adaptive adjustment of predistortion for the amplifiers of the phased array can be based on a signal derived from the combined RF sample signals.

Abstract: An example apparatus includes a power amplifier (PA) and a linearity optimizer. The optimizer includes a PA actuator and a linearity adaptation circuit. The actuator is configured to generate an actuator output based on an actuator input and a vector of complex gains computed by the linearity adaptation circuit based on a feedback signal indicative of PA's output. The adaptation circuit is configured to compute the vector of complex gains in a manner that maximizes the power of the actuator output while ensuring that the deviation of PA's behavior from a linear behavior (e.g., in terms of one or more linearity parameters) is below a threshold. Controlling actuator output in a manner that maximizes its power while taking into consideration one or more linearity parameters to ensure that target linearity is achieved controls drive signals for the PA and, thus, may help in terms of PA linearity and efficiency.

Abstract: Digital predistortion (DPD) arrangements that use coding to differentiate between contributions from individual power amplifiers (PAs) is disclosed. When used with a phased antenna array having N antenna elements and N corresponding PAs, the arrangements may sequentially apply N codes to input signals provided to N PAs. Each code is a vector having N elements, where each element corresponds to a different PA in that the element is a complex gain applied to an input signal for the PA. Together, the N codes may be arranged as N rows or N columns of a matrix P. The disclosed arrangements may generate N feedback signals by applying the matrix P to a signal generated by a probe antenna element sensing wireless RF signals transmitted by the N antenna elements, and to update DPD coefficients based on the N feedback signals. The N codes may be either orthogonal or non-orthogonal.

Abstract: Apparatus and methods provide predistortion for a phased array. Radio frequency (RF) sample signals from phased array elements are provided along return paths and are combined by a hardware RF combiner. Phase shifters are adjusted such that the RF sample signals are phase-aligned when combined. Adaptive adjustment of predistortion for the amplifiers of the phased array can be based on a signal derived from the combined RF sample signals.

Abstract: An apparatus that implements DPD in a manner that can address OOB instability issues, PE instability issues, or both, is disclosed. The apparatus includes an actuator circuit configured to use a model of a power amplifier (PA) to apply a predistortion to at least a portion of an input signal, and an error correction circuit configured to generate an error signal indicative of a deviation of the output of the actuator circuit from the target output, e.g., in terms of OOB or PE. The apparatus also includes an adaptation circuit configured to update the model based on the error signal. By using such an error in adapting the model used for the DPD, undesirable effects of performing DPD, such as creation or amplification of OOB frequency components, or increasing amplitude of some samples, may be reduced or eliminated.

Abstract: An apparatus that implements DPD in a manner that can address OOB instability issues, PE instability issues, or both, is disclosed. The apparatus includes an actuator circuit configured to use a model of a power amplifier (PA) to apply a predistortion to at least a portion of an input signal, and an error correction circuit configured to generate an error signal indicative of a deviation of the output of the actuator circuit from the target output, e.g., in terms of OOB or PE. The apparatus also includes an adaptation circuit configured to update the model based on the error signal. By using such an error in adapting the model used for the DPD, undesirable effects of performing DPD, such as creation or amplification of OOB frequency components, or increasing amplitude of some samples, may be reduced or eliminated.

Abstract: Various examples are directed to systems and methods for generating a real-mode predistorted signal. A digital predistortion (DPD) circuit may receive a real-mode signal comprising a linear portion and a nonlinear portion. The DPD circuit may generate a real-mode predistorted signal based at least in part on the real-mode signal.

Abstract: Otherwise incompatible crest factor reduction (CFR) and cable tilt compensation can be used together, such as in a cable television or other cable communication system having a frequency-dependent signal loss at higher frequencies. The CFR can be used to limit or reduce peaks of signals provided to a power amplifier, while additional tilt reference and tilt equalizer circuits are included to address deleterious peak regrowth effects that may otherwise arise by using conventional CFR together with cable tilt compensation.

Abstract: An example communication system includes a frequency-segmented power amplifier (PA) circuit that includes a plurality of PA segments. Each PA segment is configured to amplify a portion of a PA input signal in a different frequency band to generate a respective output signal (PA segment output signal). The frequency-segmented PA circuit further includes a combiner, configured to combine PA segment output signals from different PA segments to provide a power-amplified version of the PA input signal. Implementing such a frequency-segmented PA circuit may result in significant improvement in PA efficiency.

Abstract: Various examples are directed to a power amplifier circuit, comprising a digital predistortion circuit, first and second power amplifiers, and a bias feedback circuit. The digital predistortion circuit may be configured to generate a predistorted input signal based at least in part on an input signal. The first power amplifier may be configured to generate a first amplified signal based at least in part on the predistorted input signal. The second power amplifier may be configured to generate a second amplified signal based at least in part on the predistorted input signal. The bias feedback circuit may be configured to adjust at least one of a bias of the first power amplifier or a bias of the second power amplifier to align a first nonlinear behavior of the first power amplifier with a second nonlinear behavior of the second power amplifier.

Abstract: Transmitter noise cancellation may be applied on a channel by channel basis to active channels of an incoming radio frequency signal received at a receiver. A noise cancellation filter may be provided for each active channel in a predetermined signal band. Applying noise cancellation on a per active channel basis instead of to the entire receive band may substantially reduce the filtering requirement and number of filter coefficients or taps to save power and reduce manufacturing costs. Channelized transmitter noise cancellers, multi transmitter-receiver cross coupling cancellers, and hybrid full signal band and channelized transmitter noise cancellers are also provided.

Abstract: Various examples are directed to systems and methods for digital predistortion (DPD). A linear digital predistortion (DPD) circuit may be programmed to generate a pre-distorted signal linear component based at least in part on a complex baseband signal. A nonlinear DPD circuit may be programmed to generate a pre-distorted signal nonlinear component based at least in part on the complex baseband signal. A mixer circuit programmed to generate a pre-distorted signal based at least in part on the pre-distorted signal linear component and the pre-distorted signal nonlinear component.