Design of a Low-Voltage CMOS Mixer with Improved Linearity

This paper presents a low-voltage CMOS (complementary-metal-oxide-semiconductor) mixer with low power consumption. By using the folded-cascade structure, the problem on high supply voltage of the stacking transconductance-stage and switching-stage is solved. Firstly, a differential cross-coupling structure is used to improve transconductance-stage’s linearity without decreasing voltage margin. Then, two inductors are used as the RF (Radio Frequency) choke, which could prevent the leakage of the input RF signal at design frequency without consuming direct-current voltage. Finally, the low-voltage CMOS folded-cascade mixer is designed and verified on a TSMC 0.18 um RF CMOS process. The simulation results show that the mixer features a conversion gain of 15.8 dB, a noise figure of 11 dB, a third-order input intercept point (IIP3) of 1.4 dBm, and consumes only 3 mW at a power supply voltage of 1.2 V.