Broad-Band Power Amplification with Gunn-Effect Diodes

Coherent single-frequency amplification has been obtained from supercritically doped (n₀l >10¹² cm_-2) Gunn-effect devices biased above threshold. Heavy circuit loading was employed such that the diodes oscillated weakly near the transit-time frequency. A sufficiently strong input signal suppressed the self-oscillation and was amplified. Useful amplification was obtained in the saturation region with the output power comparable to that obtainable from the diode as an oscillator. The frequency response and saturation characteristics of a reflection amplifier in X band are described. Useful bandwidths from 1 to 16 percent with power gains from 11 to 4 dB were observed for a single diode. FM and AM noise spectrum measurements are also presented.