A 79 GHz gm-boosted sub-harmonic mixer with high conversion gain in 65nm CMOS

In this paper, a 79 GHz gm-boosted sub-harmonic mixer with high conversion gain is presented. As a gm-boosting technique, a transformer based feedback network with an NMOS bleeding path is proposed to achieve high conversion gain. The differential LO-driven sub-harmonic mixer has a simple structure and operates at low LO power. The measurement results show a conversion gain of 1.6 dB at a LO power of −5 dBm, a noise figure of 13 dB, and a 2LO-to-RF isolation of 38 dB. The power consumption of the sub-harmonic mixer is 12 mW. The circuit was fabricated using 65-nm CMOS technology with a chip area of 0.69×0.45 mm².