A monolithic W-band CPW rat-race mixer with HBT IF amplifier

This paper reports on a fully monolithic W-band Schottky diode downconverter with an IF amplifier using heterojunction bipolar transistors (HBTs). We use a coplanar waveguide (CPW) as a transmission line element for a rat-race, because a CPW requires one-side wafer processing only. The conversion gain is +9.5 dB with the HBT amplifier and -8.8 dB without the HBT amplifier at an RF of 95 GHz. The isolation from the LO port to the RF port is 29 dB with the HBT amplifier and 27 dB without the HBT amplifier.