Analog Devices International Unlimited Company

Analog Devices Global Unlimited Company

David Jennings

Patrick Joseph Pratt

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.

Multi-component digital predistortion

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.

Digital predistortion with out-of-band and peak expansion regularization

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.

Crest factor reduction in cable communication systems

Various examples are directed to a digital predistortion (DPD) circuit comprising a DPD actuator circuit, a DPD feedback frequency-shaping filter, a basis matrix generator circuit, a basis matrix frequency-shaping filter, and a DPD adaption circuit. The DPD actuator circuit may generate a predistorted signal based at least in part on an input signal and a set of frequency-shaped DPD parameters. The DPD feedback frequency-shaping filter may filter a DPD feedback signal to generate a frequency-shaped DPD feedback signal. A passband of the DPD feedback frequency-shaping filter may include substantially all of a bandwidth of the input signal and exclude a distortion term outside the bandwidth of the input signal. The basis matrix generator may generate a basis matrix based at least in part on a power amplifier feedback signal The basis matrix frequency-shaping filter may generate a frequency-shaped basis matrix based at least in part on the basis matrix. The DPD adaption circuit may be configured to generate the set of frequency-shaped DPD parameters based at least in part on the frequency-shaped basis matrix and the frequency-shaped DPD feedback signal.

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Bristol, United Kingdom

David Jennings