K-Band CMOS Variable Gain Amplifier Using Supply Voltage Tuning Method for Wide Gain Range

A K band two-stage Variable Gain Amplifier (VGA) with a supply voltage tuning method is presented in this paper. The proposed VGA consists of a first stage and second stage, designed to achieve wide gain control with minimized phase variation. Implemented in a 65-nm CMOS process, the VGA is optimized for beamforming transceivers in satellite communication and mm-Wave 5G applications. Simulation results show a gain control range of 10 dB with a maximum phase variation of less than 1.91°, ensuring stable operation in phased array systems. The VGA also achieves input and output return losses (S11, S22) below -10 dB. The proposed design demonstrates superior gain resolution and phase stability compared to conventional structures.