Buildup behaviour of IMPATT oscillators in linear and nonlinear ranges

The growth rate, frequency shift and starting amplitude of oscillations in IMPATT-diode oscillators are calculated in the linear and nonlinear range. It turns out that, with increasing r.f. amplitude, the frequency in such oscillators always decreases, and that this frequency shift cannot be compensated for by proper tuning of the load. The r.f. amplitude remains below the measurable level for a certain time depending on the oscillator tuning. This accounts for the observed delay of the onset of the r.f. pulse.