A 1.2-GHz bandwidth variable gain amplifier with continuous dB-linear control in 65nm CMOS

In this paper, a wideband variable gain amplifier (VGA) is designed in 65nm CMOS technology. The proposed VGA is composed of two cascading variable gain cells. Each gain cell employs a simple single-stage pseudo-exponential topology to realize continuous decibel in linear gain control and low power consumption. Two cascading cells realize a VGA with more than 50dB decibel in linear gain tuning range and 1.2-GHz-3dB bandwidth. The proposed wideband VGA consumes about 1.2mA current from a single 1.2V supply and is suitable for analog baseband signal processing in 60-GHz wireless communication systems. Furthermore, the proposed design is realized only based on CMOS devices without inductor and resistor which means small area and insensitive to process variation.