A V-band variable gain amplifier with low phase variation using 90-nm CMOS technology

A V-band variable gain amplifier (VGA) with wide gain control range, low phase variation, and low return loss variation is designed and implemented on 90-nm CMOS process. Utilizing a phase compensation capacitor at the common gate transistor and a source degeneration inductor at the common source transistor of the cascode configuration, the VGA achieves gain control range of 15.8 dB with only 6.9° transmission phase variation at 60 GHz via simple control mechanism. The maximum small signal gain is 15.8 dB at 60 GHz. In addition, the input/output return losses are insensitivity at different gain state of the VGA.