Two-port microwave amplification in long samples of gallium arsenide

Experiments on a new type of two-port, unilateral traveling-wave amplifier using subcritically doped GaAs specimens several space-charge wavelengths long are described. Net terminal gains of 2-4 dB are reported in the frequency range 700-1500 MHz. The gain is presently limited by inefficient coupling to the space-charge wave; the measured variation of phase delay between input and output terminals as a function of bias voltage is in good accord with theory, however.