94GHz Single-balanced Diode Mixer for FMCW Radar applications

In this paper, we present a high performance 94 GHz MMIC diode mixer using a 100-nm metamorphic high electron mobility transistor (MHEMT) diode and coplanar waveguide (CPW) 3-dB tandem coupler. A novel single-balanced structure of MHEMT diode mixer was proposed in this work, and 3-dB tandem coupler with the air-bridge structure was used for broadband LO-RF isolation. The fabricated mixer has LO-RF isolation, greater than 19 dB, in 15 GHz bandwidth of 82-97 GHz. The good conversion loss of 14.8 dB was measured at 94 GHz.