A 60-GHz bi-directional variable gain amplifier with microstrip-line interconnect in 65 nm CMOS

A 60-GHz switchless bi-directional variable gain amplifier (BDVGA) is presented in this paper. The proposed RF signal flow direction and amplifier gain reconfigurable design is implemented by using micro-strip line (MSL) structure as interconnects between two back-to-back connected identical amplifiers and the transistor bias voltage control. Hence, the proposed 2-port bi-directional amplifier avoids the lossy and bulky high frequency switch and achieves an improved forward gain, noise figure, linearity, return losses and isolation performance over a wide frequency range from 55 to 66 GHz. The design is fabricated in Global Foundries 65 nm CMOS process and occupy 0.48 mm2 core die area.