A new structure of the variable gain amplifier using CMOS technology

Abstract

This paper proposes a solution for a variable gain amplifier (VGA) using 0.35 μm CMOS technology. In order to increase linearity and noise performance, the VGA has been designed based on the configuration of differential amplifier. The gain is altered under a pseudo-exponential function following the control of a current source supplied to a source-coupled differential pair with diode-connected load. The simulation results indicate that the gain is varied continuously and linearly in a range from 8 dB to 21 dB when the controlled voltage varies from 1.4 V to 3.8 V, and the bandwidth of the VGA is proposed higher than 250 MHz.