Abstract: A feed-forward system for reducing the distortion products from a device such as an amplifier, wherein samples of the distortion products from the output of the device in one or more frequency bands whose bandwidths are less than that of the device are extracted, adjusted in amplitude and phase and subtractively combined with the device output to produce a system output in which distortion in the frequency bands is reduced.

Abstract: A feed-forward system for reducing the distortion products from a device h as an amplifier, wherein a sample of the device input signal is subtractively combined with a sample of the device output signal to produce a sample of the distortion products. The distortion sample is adjusted in amplitude and phase and subtractively combined with the device output to produce a distortion-reduced system output. A synchronous detector correlates a sample of the system output, in which the proportion of distortion has been increased, with another sample of the distortion products to produce control signals for a modulator which adaptively adjusts the amplitude and phase of the distortion sample subtractively combined with the device output.

Abstract: A feed-forward amplifier in which samples of the input and output signals a main amplifier are adjusted in amplitude and algebraically combined to produce a sample of the error introduced into the output signal by distortion and noise in the main amplifier. This error sample is amplified to produce a correction signal by a subsidiary amplifier which itself introduces noise and distortion. The correction signal is algebraically combined with the output signal of the main amplifier and a fraction of the resultant output signal is fed back to the input of the subsidiary amplifier to render the output signal substantially free of error caused by either of the main and the subsidiary amplifiers.