Development of high efficiency frequency multipliers

A frequency multiplier combined with a fundamental solid state oscillator is an attractive choice for the local oscillator of a low noise mm- or submm-receiver in space applications. A Schottky diode in the varactor mode provides the best multiplier element up to 500 GHz and in the varistor mode from 500 to 800 GHz. At 100 GHz efficiencies as high as 45 % for a doubler and 28 % for a tripler have been demonstrated experimentally at the Helsinki University of Technology. A stacked GaAs p-n varactor and a GaAs resonant tunneling (quantum well) diode are new interesting multiplication elements for mm-waves.