A 3 V linear input range tunable CMOS transconductor and its application to a 3.3 V 1.1 MHz Chebyshev low-pass Gm-C filter for ADSL

Abstract

A fully differential CMOS transconductor with 3 V linear input range is proposed. The Gm value of the transconductor is tunable through a current division scheme. A current mode arithmetic method is used to adaptively bias the transconductor tuning stage. A 3.3 V 1.1 MHz Chebyshev low-pass Gm-C filter using this highly linear transconductor achieves a IM3 distortion at 300 kHz of -62 dBc for a 2 Vppd input signal. The filter was fabricated with a double poly triple metal 0.35 /spl mu/m CMOS process and consumes 66 mW.