Digitally implemented predistorter control mechanism for linearizing high efficiency RF power amplifiers

A method of reducing the effects of intermodulation distortion of an RF power amplifier comprising the steps of:

• (a) coupling an RF input signal to be amplified by said RF power amplifier to an RF predistortion unit that is controllably operative to adjust the RF input signal applied to said RF power amplifier;
• (b) generating predistortion model that approximates an inverse of the transfer characteristic of said RF power amplifier, including a first signal processing operator that compensates for static non-linearities, and a second polynomial-based signal processing operator that compensates for dynamic memory effects in the amplifier's non-linear transfer characteristic;
• and
• (c) controlling said RF predistortion unit in accordance with said first and second signal processing operators so as to predistort said RF input signal and compensate for distortion effects of said RF power amplifier.

An RF power amplifier apparatus comprising:

• an RF power amplifier coupled between an RF input port and an RF output port and being operative to amplify an RF signal applied thereto so as to produce an amplified RF output signal;
• a vector modulator coupled to receive said RF input signal and being controllably operative to adjust the RF input signal applied to said RF power amplifier;
• and
• a digital signal processor (DSP), which is programmed to execute a first signal processing operator in terms of a digital polynomial-based predistortion function that approximates an inverse of dynamic memory effects in the nonlinear transfer characteristic of said RF power amplifier, said digital polynomial-based predistortion function being used to control said vector modulator in a manner that predistorts said RF input signal to compensate for said dynamic memory effects of the nonlinear transfer characteristic of said RF power amplifier.