A Low Power, Low Voltage, Fully Differential CMOS Variable Gain Amplifier

This research presents a low voltage (0.8 V) fully differential CMOS variable gain amplifier. SPECTRE simulations on the designed amplifier show a -17 dB to 20 dB gain variation in 1 dB steps, with a mean gain error of 0.0714 dB. SPECTRE simulations also reveal a 1 dB compression point of -15.3 dBm and 3rd order input intercept point of -1.38 dBm at a gain of -17 dB. The entire variable gain amplifier consumes a maximum of 40 µW of power at the highest gain. The proposed configuration has rail-to-rail input common mode range and a class AB output stage to maximize signal swing. The variable gain amplifier is shown to be highly robust against process, temperature, and input common mode voltage variations and is designed using a 45nm standard CMOS process