An Inherently dB-linear All-CMOS Variable Gain Amplifier

Abstract

This paper introduces a simple variable gain amplifier (VGA) structure that shows an inherently dB-linear gain control property. Requiring no additional components for dB-linear control, the structure is compact and power efficient. The designed two-stage VGA shows a gain control range of 60dB with the gain error in the range of +/- 0.4 dB. The power consumption including the output buffer is 20.4 mW from 1.2 V supply voltage with bandwidth of 630 MHz. The prototype was fabricated in a 0.13. m CMOS process and the VGA core occupies 0.06 mm(2)