Panasonic Corporation

Tony L Wong

Wayne S Lee

Herb Evans

A polar modulation transmitter includes an amplitude modulation (AM) path with an amplitude modulation to amplitude modulation (AM/AM') correction circuit and a phase modulation (PM) path with a delay element and an amplitude modulation to phase modulation (AM&#x2032;/PM) correction circuit. The AM/AM&#x2032; correction circuit receives and predistorts a digital amplitude component signal depending on amplitudes of samples in the digital amplitude component signal, thereby generating a predistorted digital amplitude component signal. The delay element receives and delays a digital phase component signal, to generate a delayed digital phase component signal having a delay corresponding to the latency introduced by the AM/AM&#x2032; correction circuit. The AM&#x2032;/PM correction circuit predistorts the delayed digital phase component signal depending on amplitudes of samples in the predistorted amplitude component signal, thereby generating a predistorted digital phase component signal.

Time alignment methods and apparatus for polar modulation transmitters

Methods and apparatus for predistorting signals in a polar modulation transmitter. An exemplary method includes predistorting an envelope component signal in an amplitude path of a polar modulation transmitter according to a set of AM/AM predistortion coefficients, and predistorting a phase component signal in a phase path of the polar modulation transmitter according to a set of AM/PM predistortion coefficients. The AM/AM and AM/PM predistortion coefficients are stored in a memory in the form of a look up table (LUT). The envelope component signal is scaled and/or offset, before predistortion is applied, by an amount dependent upon which average power level of a plurality of average power levels the power amplifier of the polar modulation transmitter is configured to operate. Scaling and/or offsetting the envelope component signal prior to applying predistortion affords the ability to share the AM/AM and AM/PM predistortion coefficients of the predistortion LUT over the plurality of average power levels.

Predistortion methods and apparatus for polar modulation transmitters

Methods and apparatus for reducing the bandwidth of modulation signals in a phase path of a polar modulation transmitter. An exemplary method includes generating a phase difference modulation signal for a phase path of a polar modulation transmitter, and filtering the phase difference modulation signal using a linear-phase filter. Filtering the phase difference modulation signal may be performed by first detecting samples in the phase difference modulation signal that have phase difference values in excess of a phase difference threshold and then filtering samples in the vicinity of the threshold-violating samples to remove the threshold-violating events. Alternatively, all samples may be filtered, i.e., without regard as to whether any given sample exceeds a phase difference threshold, to remove large phase difference changes in the phase difference modulation signal, or a combination of linear-phase and nonlinear filters may be used to remove the large phase difference changes.

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Hayward, CA, United States of America

Tony L Wong