Submillimeter-wave subharmonic mixer diodes

Space-borne receivers operating in the submillimeter region of the electromagnetic spectrum generally employ subharmonically-pumped (SHP) mixers because of the lack of adequate local oscillator (LO) power at fundamental frequencies. Such mixers utilize local oscillators at one half the signal frequency where more power is usually available. However, typical SHP mixers using zero-biased anti-parallel Schottky diode pairs require a larger LO power than biased diodes. This work investigates two devices for SHP mixing for reducing the LO power requirement: planar doped barrier (PDB) diodes and separately biased Schottky diodes. These devices were fabricated using low-parasitic, air-bridge and surface channel planar-diode technology. RF measurements were performed around 200 GHz for both devices. The low-barrier-height PDB diodes show a very low LO power requirement (...