Improving linearity of CMOS Gilbert-cell mixers using body biasing

This paper presents the application of body biasing to improve linearity performance of CMOS Gilbert-cell mixers. In order to improve the linearity, the bulk bias voltage of the transistors in the local oscillator (LO) stage is adjusted. The improvement in linearity is obtained while the conversion gain and power consumption of the mixer remain virtually intact. A 0.13-μm CMOS proof-of-concept prototype is implemented which operates at radio frequency (RF) of 2.4 GHz with an intermediate frequency (IF) of 50 MHz and draws 2.25 mA from a 1.2-V supply. Based on post-layout simulations, the proposed technique results in a 5-dB improvement in the input-referred third-order intercept point (IIP3) of the prototype mixer.