A 270MHz, 1 Vpk-pk, low-distortion variable gain amplifier in 0.35 µm CMOS process

A fully balanced CMOS Variable Gain Amplifier (VGA) for high frequency applications and large signals is presented. The VGA consists of an analog multiplier, current gain stages, and resistive loads. A frequency compensation scheme based on a capacitive feed-forward technique increases the bandwidth by more than 60 %. Common-Mode Feed-Forward (CMFF) techniques are used to minimize dc offsets. The gain can be programmed from 0 dB to 42 dB with -3 dB bandwidth greater than 270 MHz. The Third Harmonic Distortion (HD3) is less than -55 dB for differential input and output voltages of 1 Vpk-pk. The VGA was fabricated in 0.35 µm CMOS process, and consumes around 54 mW from a single power supply of 2.7 V.