An all CMOS 743 MHz variable gain amplifier for UWB systems

A newly proposed variable gain amplifier (VGA) that offers wide bandwidth and gain variation characteristics is described for ultra wideband system applications. The proposed VGA combines a cascade-input stage and bandwidth-extension loads to obtain a wide bandwidth. The VGA is simulated in 0.13 /spl mu/m CMOS technology and simulations show a gain variation range of 54 dB in a single-stage VGA and a minimum 1-dB bandwidth of 743 MHz at the maximum gain of 20 dB. The 1-dB bandwidth improvement of 58% compared to conventional VGAs at the same supply current is obtained. In addition, the newly proposed control stage results in a compact VGA, which leads to low power consumption. The VGA dissipates an average supply current of 4.5 mA from 1.8 V supply voltage.