Automatic gain control

Voltage

Engineering

Variable-gain amplifier

Materials science

Transimpedance amplifier

Resistor

Operational amplifier

Amplifier

Video Graphics Array

Fully differential amplifier

Transistor

Physics

Transconductance

Electronic engineering

Direct-coupled amplifier

Open-loop gain

CMOS

Operational transconductance amplifier

Optoelectronics

Electrical engineering

AEU - International Journal of Electronics and Communications

A compact low-power low-voltage CMOS variable gain amplifier (VGA) is proposed. The proposed circuit merges a source-degenerated transconductance amplifier with a current-mode transimpedance amplifier, which renders voltage gain control with constant bandwidth. Coarse gain tuning is achieved by using a switched-resistor network, while fine gain tuning is obtained by using a voltage-controlled active resistor. A two-stage VGA was fabricated in a 0.35μm CMOS technology. Experimental results show that the prototype VGA has a gain range of 40 dB with more than 10 MHz bandwidth, while draining only 600μA from a 1.5 V supply voltage.

Low-voltage compact CMOS variable gain amplifier