A 340-GHz Upconversion Mixer MMIC Using an Antiparallel Series Schottky Diode Pair With High Output Power

This letter introduces a newly developed 340-GHz subharmonic upconversion mixer, utilizing GaAs monolithic integration technology, for terahertz communication and imaging systems. The mixer features a designed antiparallel series planar Schottky diode pair for high output power. To achieve wideband circuit matching and low conversion loss (CL), RF/LO <tex-math notation="LaTeX">E</tex-math> -field probe in conjunction with an IF–LO diplexer/filter is codesigned with the diode pair. This makes the proposed mixer particularly suited for mixer-last transmitter systems. The fabricated upconversion mixer has been tested, demonstrating a minimum single-sideband (SSB) CL of 9.4 dB across the 311–349-GHz range. Notably, it achieves a maximum output power of –6.8 dBm. To the best of authors' knowledge, this is the highest output power reported so far for subharmonic mixers at approximately 340 GHz.