A Q-BAND HIGH-GAIN, LOW-NOISE VARIABLE GAIN AMPLIFIER USING DUAL-GATEALGAAS INGAAS PSEUDOMORPHIC HEMTS/

A Q-band high gain and low noise Variable Gain Amplifier (VGA) module using dual gate AlGaAs/InGaAs pseudomorphic HEMTs has been developed. The dual gate HEMT can be fabricated by the same process of the single gate HEMT which has the gate length of 0.15 mu m. The Q-band VGA modu le consists of a 1-stage low noise amplifier (LNA) MMIC using a single gate HEMT and a 2-stage VGA MMIC using dual gate HEMTs. During the de sign, an accurate noise modeling is introduced to achieve low noise pe rformance. A fully passivated film is employed to achieve reliability. The VGA module has a gain of more than 20 dB from 41 GHz to 52 GHz an d a maximum gain of 24.5 dB at 50 GHz. A gain control range of more th an 30 dB is achieved in the same frequency range. A phase deviation is less than 10 degrees in 10 dB gain control range. A minimum noise fig ure of 1.8 dB with an associated gain of 22 dB is achieved at 43 GHz a nd the noise figure is less than 2.5 dB with associated gain of more t han 20 dB from 41 GHz to 46 GHz when biased for low noise figure. This performance is comparable with the best data ever reported for LNAs a t Q-band including both GaAs based HEMTs and InP based HEMTs.