A CMOS Low-noise Active Mixer with Capacitive Neutralization Technique

Abstract

a broadband CMOS active down-conversion mixer is presented. Specifically, a capacitor cross-coupled transconductor serves as the input stage to reduce noise figure of the mixer while providing wideband input matching. Moreover, a capacitive neutralization technique is used to compensate the source-drain parasitic of input stage and boost loop gain of the transconductor, resulting in improved isolation and linearity. The current-reuse technique applied to the developed transconductor by stacked nMOS/pMOS architecture efficiently saves power consumption of the circuit. Implemented in the TSMC 28-nm CMOS process, post-simulations show that, the proposed mixer provides a maximal conversion gain of 11.4 dB and a NF of 3.9~4.7 dB across RF input frequency range of 2~9.6 GHz. The average IIP3 of 5 dBm are obtained while the mixer core consumes 6.2 mW.