A simple class-AB transconductor in CMOS

In this paper, we present a simple class-AB CMOS transconductor, which is based on Delbriick´s bump/antibump circuit, whose differential output current is an expansive nonlinear function of its differential-mode input voltage. We describe the operation of the new transconductor qualitatively and derive an analytical model of its output currents from the Enz-Krummenacher-Vittoz (EKV) model of the MOS transistor. We also provide experimental measurements of the DC transfer characteristics of a version of the circuit that was fabricated in a 0.5-mum CMOS process through MOSIS.