A wideband linear-in-dB VGA using a CMOS in the triode region

Abstract

This paper presents a wideband variable gain amplifier (VGA) fabricated using the 0.18-mu m CMOS process. An exponential CMOS triode transconductor scheme is proposed to achieve highly linear-in-dB characteristics of a VGA for ultra-wideband (UWB) systems. The proposed VGA achieves a linear-in-dB controllable gain range of 28.4 dB (7 to -21.4 dB) with a bandwidth of 1200 MHz, while drawing only, 2.7 mA from a 1.8-V power supply. Measurements show a linear gain range with a linearity error of less than +/- 0.5 dB. P-1dB varies from -8.5 to -6 dBm. The chip occupies an area of 0.2 x 0.2 mm(2), excluding bond-pads. (c) 2006 Wiley Periodicals. Inc.