Analysis and design of a 1.0-V CMOS mixer based on variable load technique

A CMOS active mixer based on variable load technique which can operate at 1.0 V supply voltage is proposed and its operation principle, noise and linearity analysis are presented. Different from the conventional Gilbert mixer based on RF current-commutating, the proposed mixer controls the load impedance according to the LO signal. It has only two stacked transistors at each branch which is suitable for low-voltage applications. The mixer was fabricated in 0.18-μm0.18-μm 1P6M CMOS process and measured in 2.4-GHz ISM band. With an input 2.440 GHz RF signal and a 2.442 GHz LO signal, the conversion gain is 5.3 dB, the input-referred third-order intercept points is 4.6 dBm, the input-referred 1 dB compression point is −7.4 dBm, and the single-sideband noise figure is 21.7 dB. Total DC current consumption is 3.5 mA.