Circuit model for TRAPATT-oscillator cavities

The paper presents an analysis of the class of TRAPATT-oscillator circuit in which the avalanche diode is mounted at the end of a transmission line at a distance of approximately one halfwavelength (at the fundamental frequency of the oscillation) from a filter. This paper is concerned with the transformation of the current and voltage waveforms at the input to the cavity filter into the waveforms at the diode. It is shown from the transformation how the diode voltage consists of an extraction waveform and a trigger waveform. Expressions are derived which express the parameters of the trigger waveform in terms of circuit parameters. Consideration of the extraction waveform leads to the construction of a mode chart, which determines the bias current and voltage limits of the mode of operation. An analysis is developed which examines the properties of the mode chart and which is used to examine a cavity containing a filter with an exponential response.