Broadband amplifier with quadrature pilot signal

摘要

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.