Computer simulation of InP transferred-electron amplifiers for Ka-band

A displaced Maxwellian approach which includes relaxation effects is used to simulate small- and large-signal InP transferred-electron amplifiers operating in -band. The devices considered are short-circuit stable; that is, they have a subcritical doping-length product. The performance of amplifiers having the usual n⁺-cathode contacts, and p-type notch-cathode contacts designed to produce a uniform electric field, are compared. It is found that the notch contacts have a moderate influence on small-signal characteristics, and a profound influence on large-signal performance. Small-signal bandwidths of 65 percent are predicted for both types of contacts. The saturation efficiency of amplifiers, biased at three times threshold, is much higher for the notch-contact device with values near 5 percent being predicted. The nonlinearity of the large-signal gain characteristic is shown to vary greatly as the frequency deviates from the optimum value.