380GHz Sub-Harmonically Pumped Mixer Based on Anti-Parallel Planar Schottky Diode

This paper presents the design and fabrication of a feed horn antenna integrated fix-tuned 380GHz sub-harmonically pumped mixer, based on planar GaAs air-bridged Schottky anti-parallel diode from Rutherford Appleton Laboratory. The diode was designed and fabricated by millimeter technology group, Rutherford Appleton Laboratory, UK. The mixer’s circuit configuration and cavity block are realized by joint simulation of ANSOFT’s three-dimensional full-wave electromagnetic simulation software HFSS and AGILENT’s circuit simulation software ADS. The mixer circuit is fully integrated with the microstrip circuit and the flip-chipped diode on suspended 50μm thick quartz substrate, and whole fixed-tuned mixer cavity block is integrated with RF feed horn antenna, using least parts to minimize the cost, as well as maximize its potential convenience for circuit and block manufacture. The simulation and test investigation have good agreement and show state-of-the-art results. The experimental results show that over an IF band of 2.5–3.5 GHz, the mixer’s conversion loss is lower than 10 dB with mean value 9 dB, and the mixer’s equivalent noise temperature is less than 3000 K with mean value 2000 K. Besides, mixer equivalent noise temperature curve’s variation trends show good consistency with conversion loss curve.