Abstract
The theory of nonlinear fundamental and subharmonic resonances in the avalanche region of IMPATT diodes is developed by use of the method of harmonic balance. Due to the high resonance strength of the subharmonic mode, and as a consequence of large-signal parametric interaction, the negative resistance of the diode is markedly increased at the presence of a self-pumped oscillation of twice the frequency of the fundamental mode, especially for low-transit angles across the drift region.