A 5.2 GHz 16 dB gain CMFB Gilbert downconversion mixer using 0.35 μm deep trench isolation SiGe BiCMOS technology

A 16 dB conversion gain, IP_1dB=-21 dBm and IIP₃=-11 dBm Gilbert downconversion micromixer when RF=5.2 GHz and LO=5.17 GHz is demonstrated by using 0.35 μm SiGe BiCMOS technology. The input return loss is better than 13 dB for frequencies up to 10 GHz. Active PMOS loads with common mode feedback to stabilize the bias points is used in the Gilbert mixer loads to increase the mixer gain. An IF NMOS differential amplifier converts the differential output into a single-ended output. SiGe HBTs possesses good device matches and the SiGe BiCMOS technology has deep trench isolation technique to improve the port to port isolation. Finally, an off-chip rat-race coupler provides balanced LO signals to facilitate isolation measurement. -66 dB LO-IF, -52 dB LO-RF and -24 dB RF-IF isolations for a downconversion micromixer are achieved.