MHMIC Six-port Interferometer for W-band Transceivers: Design and Characterization

Abstract

The study has presented an extensive analysis of an integrated millimeter wave six-port interferometer, operating over a 10 GHz band, from 80 to 90 GHz. It has covered both semi-unlicensed point-to-point links (81-86 GHz), and imaging sensor system frequencies (above 85 GHz). An in-house process is used to fabricate miniaturized hybrid millimeter wave integrated circuits on a very thin ceramic substrate. Two-port S-parameter measurements are performed on a minimum number of circuits integrated on the same die, exploiting the circuit’s physical symmetry and chosen to collect enough data for full-port characterization. Based on these measurements on an integrated prototype, a six-port circuit computer model implemented and advanced system simulations performed for circuit analysis. Interferometer performances evaluated using several methods: analysis of harmonic balance, qi points’, homodyne quadrature demodulation, and error vector modulation (EVM). The analysis showed that this circuit can directly perform, without any calibration, the demodulation of various PSK and QAM signals over the 10 GHz band, with very good results.

Millimeter Wave Multi-Port Interferometric Radar Sensors: Evolution of Fabrication and Characterization Technologies

“…All unused ports are loaded using integrated resistors of characteristic impedance value. Via-holes are avoided for grounding in order to reduce parasitic elements and to ensure the measurements’ repeatability [ 40 , 83 ]. Broadband RF short circuits implemented with quarter waveguide open stubs are used instead.…”

“…This works demonstrated that, despite the claims of some experts, microstrip technology can be successfully used at these higher frequencies by appropriate choice of a good quality, very thin substrate, transmission line characteristic impedances, and components’ shape. Authors claimed that, when fabricated in 2014, this was the first MHMIC multi-port operating at more than 80 GHz [ 83 ].…”

“…In order to perform system simulations with realistic behavior, computer models based on S-parameter measurements must be implemented into design and analysis software, for example the advanced design system (ADS) of Keysight Technologies. All two-port VNA S-parameter measurements of the MHMIC multi-port are imported as Data Access Components (DAC) [ 83 ].…”