Abstract: The invention relates to an amplifier arrangement for amplifying an input signal using a distorting main power amplifier such as one operating as a class AB amplifier. The amplifier can be biased at different operating points. The method and apparatus modify bias control signals to the main amplifier to reduce or minimize the distortion energy added by the main power amplifier. A digitally controlled processor iteratively modifies various control bias signals to adjust the output of the amplifier. Different gain and phase control lines can also be iteratively updated at different rates.

Abstract: A broadband feed-forward amplifier configuration includes an amplifier having an input and an output. A comparison loop compares the signal output to the amplifier with a signal input to the amplifier to generate an error signal and this error signal is inverted, processed, and amplified to provide a correction signal at the output of the amplifier (the cancellation loop). In the cancellation loop and at the input of the main amplifier, the circuit includes gain and phase correction circuitry for correcting small variations in amplitude and phase. A quadrature modulated pilot signal is injected at the input to the main amplifier path and is cancelled in the output to generate control signals for controlling the gain and phase correction circuits within the cancellation loop and within the main amplification loop.