Monolithic millimetre-wave oscillator using a transmission line periodically loaded by QWITT diodes

Abstract

A small-signal analysis of a travelling-wave structure implemented by periodically loading a parallel-plate waveguide with either resonant tunnelling or QWITT diodes is presented. A small-signal equivalent circuit is used to determine the diode impedance as a function of frequency. The periodicity of the structure, i.e. the distance between adjacent diodes, determines the oscillation (resonant) frequency of the circuit. The analysis shows that change in the oscillation frequency through variation in the design width and thickness of the waveguide is minimal. The physical dimensions of the waveguide facilitate monolithic fabrication of the oscillator circuit.