A 1.5mA 470MHz CMOS variable gain amplifier for wideband communication

A low power inductorless variable gain amplifier (VGA) for wideband communication systems is presented in this paper. It is a resistor feedback close-loop amplifier based on a proposed wideband operational amplifier. The operational amplifier is constructed by an artificially differential N/P complementary cascode amplifying stage for high gain, and a self-biased N/P complementary source follower for buffer stage to dramatically extend the bandwidth. The proposed VGA is implemented in the standard 0.18 ¿m CMOS process, and achieves a 3-dB bandwidth of 470 MHz for 20 dB gain, and also achieves 16 dB NF. It consumes 1.5 mA current from 1.8 V supply voltage (excluding the output buffer for measurement), and the core occupies 0.3 mm² silicon area.