A high isolation W-band MMIC drain type cascode single balanced mixer

We present a high isolation W-band MMIC drain type cascode single balanced mixer of high LO-to-RF isolation and wide band with conversion characteristic using the high directivity monolithic tandem couplers and 0.1 μm GaAs-based metamorphic high electron mobility transistors (MHEMTs). The fabricated mixer consists of two cascode MHEMT mixers and two tandem couplers using the air-bridge crossovers. We establish a drain type cascode mixer structure where the LO signal is applied to the drain port in the mixing component of common source MHEMT circuit. The tandem coupler exhibits good couplings (2.92–3.8 dB), low return losses (−32.7 dB), and isolations (15.4–39.2 dB) in a wide bandwidth of 75–110 GHz. The mixer shows a conversion loss of 9.8 dB at 94 GHz, an output P1dB of −14.8 dBm at LO frequency of 94.542 GHz, and LO-to-RF isolations of 29.5–39.5 dB at 94–100 GHz.

► We present a wide band and high isolation mixer for radar and sensor systems.
► We designed and fabricated MHEMT and tandem coupler to the mixer circuit.
► We designed the mixer circuit using the MHEMT and the tandem couplers.
► Our mixer showed better performance compared to other mixers reported to date.