A 1.8-GHz double-balanced CMOS receiver front-end

Two different mixers are compared in a differential 1.8-GHz CMOS receiver front-end with an LC tuned LNA. In the first mixer, each mixer switch is implemented with a single CMOS transistor. To decrease LO feed-through, each switch in the second mixer is implemented with a balanced complementary CMOS transmission gate. According to simulations with a 20 mV ΔV_T mismatch between the transistors in the mixer, the LO feed-through of the second implementation is more than 20 dB better than that of the first implementation. Simulations with a 3 V supply gives 15 dB gain, 25 mA current consumption, 2.1 dB NF (including gate induced noise), 0 dBm 1 dB compression point and +10 dB 1P₃