Multi-stage variable gain amplifier for low-voltage CCD analog-front end using CDA technique

Abstract

Abstract:A new technique adopting the correlated-double amplification (CDA) to improve the signal swing of the "linear-in-dB" variable gain amplifier (VGA) under a low-voltage supply is presented. This technique significantly reduces the finite op-amp gain requirement without compromising the speed. An efficient 3-stage VGA is introduced for the signal to swing up to 2/3 of the supply voltage by incorporating 2-stage push-pull op-amps. A design in a 0.13 μm CMOS process under 1.2 V supply is proposed and verified.