High gain CMOS Gilbert downconverter with wide-swing cascode current-mirror transconductor and load

Abstract

A downconversion micrornixer with low-voltage cascode current mirrors at both transconductor and load stages has been implemented using the 0.18-mu m CMOS technology in this paper, This micromixer has a single-to-differential RF input transconductance stage formed by the NMOS wide-swing cascode current mirror. PMOS wide-swing cascode current mirror is also employed to improve conversion gain while a super source follower is used at the output to reduce the output impedance and to transfer more power to the load. The fully integrated downconverter functions at 7 GHz and has the high conversion gain of 16 dB and high LO-to-IF isolation of 50 dB at 1.8 V supply voltage. The current consumption of the mixer core is I m-A. Thanks to the low-voltage operation property of the wide-swing cascode current mirror, six transistors can be stacked within 1.8 V supply voltage.