A 75–85 GHz down‐conversion mixer with integrated Marchand baluns in 90 nm CMOS with excellent matching and port‐to‐port isolation for automotive radars

Abstract

ABSTRACTA 75–85 GHz double‐balanced down‐conversion mixer for automotive radars using standard 90 nm CMOS technology is reported. The down‐conversion 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 to −19.4 dB and LO‐port input reflection coefficient of −9.1 to −11.8 dB for frequencies of 75–85 GHz. In addition, for frequencies of 75–85 GHz, the mixer achieves CG of −1 to 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. Furthermore, the mixer achieves an excellent input third‐order intercept point of 2.7 dBm at 79 GHz. These results demonstrate the proposed down‐conversion mixer architecture is promising for W‐band transceivers. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:73–80, 2015