Observation of the current and voltage waveforms of the Si IMPATT diode

Current and voltage waveforms of the Si IMPATT diode were observed directly by means of the oscillating circuit using microstrip line. The results indicate that the conventional small-signal theory cannot be applied to the observed type of oscillation. The oscillation starts at the bias voltage just above the breakdon voltage of the diode; then along with its buildup, the bias voltage is lowered owing to the auto-bias effect, to reach a steady value considerably below the breakdown voltage. Large amplitude oscillation of high efficiency is expected over a wide frequency range.