A 1GHz CMOS variable gain amplifier with 70dB linear-in-magnitude controlled gain range for UWB systems

This paper describes a design of an inductor-less variable gain amplifier (VGA) for UWB systems in a standard digital 0.18 ¿m CMOS technology. The VGA is implemented using four-stage modified Cherry-Hopper amplifier, and by changing the value of the feedback resistors in the Cherry-Hopper amplifiers, a variable gain from -17.4 dB to 52.7 dB can be obtained. The DC offset is reduced effectively by the use of dual feedback DC-offset cancellation network. The proposed VGA achieves a 3-dB bandwidth of 1 GHz with 70.1 dB gain turning range. It consumes 9 mW through a 1.8 V voltage supply. By avoiding the use of broadbanding techniques, such as peaking inductors, the amplifier cell only occupy an area of 38 ¿m × 80 ¿m (excluding the bondpads).