Abstract: A predistortion linearizer for a microwave power amplifier comprises a signal separator for receiving a signal and dividing the signal into first and second signals, a first path for carrying the first signal and a second path for carrying the second signal, and a signal combiner for combining the signals from the first and second paths. The second path between the separator and combiner includes a non-linear device for receiving the second signal and generating distortion therefrom, and a vector modulator for controlling at least one of the amplitude and phase of the second signal.