A transformer based 1.8-1.9GHz low-IF receiver for 1V in 0.13/spl mu/m CMOS

A fully integrated low-IF receiver for 1.8-1.9GHz has been realized in 0.13/spl mu/m CMOS. The receiver consists of a VCO, an IQ-divider, an LNA, and a double balanced IQ-mixer. The RF input stage and the commutating stage of the IQ-mixer are current coupled via an on-chip transformer which is operating in resonant mode and is performing a current gain. A design method is presented to reduce the input impedance of the mixer's commutating stage in order to improve the current gain of the on-chip transformer. This helps to improve the IIP3 and to reduce the power consumption. The receiver takes 25.7mA from a 1 V supply to give an IIP3 of -20.3dBm, an input referred 1-dB compression point of -30.7dBm, a conversion gain of 29.2dB and a SSB noise figure of 3.0dB.