A 1.2-V Self-Reconfigurable Recursive Mixer With Improved IF Linearity in 130-nm CMOS

A 1.2-V self-reconfigurable recursive mixer structure with improved intermediate frequency (IF) linearity and signal isolation is proposed. For a traditional recursive mixer that reuses the gm stage to amplify both the input radio frequency (RF) and downconverted IF signal, signal isolation and linearity are limited by the signal-reusing structure. In this brief, the self-reconfigurable gm stage is designed to provide open-loop V-I conversion for the input RF signal and acts as a negative-feedback voltage amplifier for the downconverted IF signal. The RF and IF signal paths are also split by the filtering networks and the feedback branches within the gm stage. Thus, IF linearity, loop stability, and signal isolation are all guaranteed. The proposed mixer was designed and fabricated in a Taiwan Semiconductor Manufacturing Company 130-nm complementary metal-oxide-semiconductor process and occupied a die area of 0.48 mm
²
. The mixer operates in the frequency band from 2 to 3 GHz with the conversion gain of around 33 dB. The measured input-referred third-order intercept point and the double-sideband noise figure are -16 dBm and 11 dB, respectively, at 2.4-GHz input frequency. The power consumption is 2.5 mW under 1.2-V supply voltage.