A CMOS low-noise active mixer with enhanced linearity and isolation by exploiting capacitive neutralization technique

Abstract

In this paper, a broadband complementary metal–oxide–semiconductor (CMOS) active down-conversion mixer is presented. Specifically, a capacitor cross-coupled (CCC) 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 an 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 from a 1 V supply.