A Q-band high gain and low noise variable gain amplifier using dual gate HEMTs

A Q-band high gain and low noise Variable Gain Amplifier (VGA) using dual gate AlGaAs/InGaAs pseudomorphic HEMTs has been developed. The dual gate HEMT can be fabricated using the same process as the single gate HEMT with a gate length of 0.15 /spl mu/m. The Q-band VGA consists of a 1-stage low noise amplifier MMIC using a single gate HEMT and a 2-stage VGA MMIC using dual gate HEMTs. The VGA has a gain of more than 20 dB from 41 GHz to 52 GHz. A gain control range of more than 30 dB is obtained in the same frequency range. A minimum noise figure of 1.8 dB with an associated gain of 22 dB is achieved at 43 GHz when biased for a low noise figure. This performance is comparable with the best data ever reported for LNAs at Q-band including both GaAs based HEMTs and InP based HEMTs.