Feedforwardߞan alternative approach to amplifier linearization

Feedforward has largely been ignored as a circuit technique since feedback was introduced in the 1920s. Modern amplifiers can benefit from the application of feedforward as well as feedback and the principle can be applied to both h.f. and X-band amplifiers. The basic principles of feedforward are described and both equations and design curves are included. Two variants of the basic feedforward arrangement are also described. One is arranged for power conservation while the other uses two identical amplifiers at full power to give a more linear output than that available from either separately. The results of these different feedforward arrangements using a pair of proprietary 30 W h.f. amplifiers are included.