Abstract

A 5.2 GHz 1 dB conversion gain, IP1dB= -19 dBm and IIP3= -9 dBm double quadrature Gilbert downconversion mixer with polyphase filters is demonstrated by using 0.35 m SiGe HBT technology. The image rejection ratio is better than 47 dB when LO=5.17 GHz and IF is in the range of 15 MHz to 45 MHz. The Gilbert downconverter has four- stage RC-CR IF polyphase filters for image rejection. Polyphase filters are also used to generate LO and RF quadarture signals around 5 GHz in the double quadrature downconverter.