Performance and theory of avalanche resonance pumped IMPATT oscillators

Avalanche diodes in multiresonant states yielding 20% efficiency at 3 GHz are described and analyzed in this paper. The silicon p⁺-n-n⁺punchthrough structure of interest has a nearly abrupt junction and a 95 volt breakdown potential. Optimum transit-time performance at 800amps/cm²is 300 mw with 10% efficiency at 9 GHz in a double-slug coaxial resonator. Under proper RF impedance conditions the operating point will switch to a current density of 2000 amps/cm². The available power at 9 GHz decreases simultaneously and subharmonic output is observed at 4.5 GHz with 6.5% efficiency. Circuits which provide for separate tuning of the fundamental and harmonic components are utilized to improve this mode. At 3000 amps/cm², 4 watts with 20% efficiency at 3 GHz is obtained with a third harmonic idler resonance.