16-GHz mHEMT double-quadrature Gilbert down-conversion mixer with polyphase filters

A 16-GHz double-quadrature very low IF down-conversion mixer with polyphase filters is demonstrated using 0.15-μm metamorphic high electron mobility transistor (mHEMT) technology. Due to the hgih cutoff frequency of mHEMT device, the image rejection Gilbert mixer works at 16 GHz. The polyphase filters are employed to generate differential quadrature signals and eliminate the image signal at RF/LO stages and IF stage, respectively, in the double quarture configuration. When RF and LO frequencies are designed around 16 GHz and an IF frequency is 32 MHz, The double-quadrature Gilbert down-converter has 32-dB image rejection ratio, 1.7-dB conversion gain, -5-dBm IP_1dB, and 5-dBm IIP₃. The die size is 3.0 mm × 3.2 mm.