Fabrication and performance of planar Schottky diodes with T-gate-like anodes in 200-GHz subharmonically pumped waveguide mixers

A T-gate-like structure has been developed, fabricated, and tested as the anode for millimeter and submillimeter wave Schottky diodes, The low parasitics of the T-anode diodes yield extremely high cutoff frequencies, making the diodes useable at frequencies well beyond 1 THz. The diodes were tested as an antiparallel-pair, integrated monolithically with microstrip circuitry on a quartz substrate, in a subharmonically pumped waveguide mixer. A double sideband noise temperature of 600 K with a conversion loss of 4.7 dB were measured at 200 GHz. This is believed to be the lowest noise temperature ever reported for a room-temperature subharmonically pumped Schottky diode mixer at this frequency.