A 640 GHz planar-diode fundamental mixer/receiver

The design and performance of a 640 GHz solid-state receiver using a fundamental planar-Schottky-diode mixer, InP Gunn diode oscillator, whisker-contacted Schottky-varactor-diode sextupler and folded-Fabry-Perot diplexer are reported. A best mixer noise temperature of 1640 K DSB, conversion loss of 8.1 dB, has been achieved at room temperature at an IF of 8 GHz and the noise is below 2100 K DSB from 1.5-11 GHz IF. Measurements employing a commercial 4-8 GHz Miteq amplifier and external bias T yield a double sideband receiver noise temperature below 3100 K from 2-8 GHz with a best value of 2720 K at 4 GHz. Measured local oscillator power was only 350 microwatts measured on a Keating acousto-optic power meter. These results are believed to represent the best reported performance for a room-temperature planar-Schottky diode receiver at this frequency.