13 mW 80 GHz down-conversion mixer with 1.5 dB gain and 49.2 dB LO-RF isolation

An 80 GHz double-balanced down-conversion mixer for automotive radars using standard 90 nm complementary metal oxide semiconductor (CMOS) technology is reported. The mixer comprises a double-balanced Gilbert cell with inductive source-degeneration radio-frequency (RF) transconductance stage for wideband RF-port input impedance matching 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 local oscillator (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 in the range 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 and LO-intermediate frequency (IF) isolation of 56.5-64.5 dB, one of the best CG and port-to-port isolation results ever reported for a CMOS down-conversion mixer with operation frequency about 80 GHz.