A W-band down-conversion mixer in 90 nm CMOS with excellent matching and port-to-port isolation for automotive radars

A W-band double-balanced down-conversion mixer for automotive radars using standard 90 nm CMOS technology is reported. The mixer comprises a double-balanced Gilbert cell with inductive source-degeneration RF transconductance stage for RF-port input matching bandwidth and conversion gain (CG) enhancement, a Marchand balun for converting the single RF input signal to differential signal, a Marchand balun for converting the single LO input signal to differential signal, and a baseband amplifier. The mixer consumes 13 mW and achieves excellent RF-port input reflection coefficient of -13.1~ -19.4 dB and LO-port input reflection coefficient of -9.1~ -11.8 dB for frequencies of 75~85 GHz. In addition, for frequencies of 75~85 GHz, the mixer achieves CG of -1~1.5 dB, LO-RF isolation of 43.5~49.2 dB, LO-IF isolation of 56.5~64.5 dB and RF-IF isolation of 35.9~39.4 dB, one of the best CG and port-to-port isolation results ever reported for a CMOS down-conversion mixer with operation frequency around 80 GHz.