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

This paper presents a wideband variable gain amplifier (VGA) fabricated using the 0.18-μm 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. P1dB varies from −8.5 to −6 dBm. The chip occupies an area of 0.2 × 0.2 mm2, excluding bond-pads. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 997–1000, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21546