A CMOS digitally programmable class AB OTA circuit

Abstract

A new low-voltage CMOS digitally programmable operational transconductance amplifier (OTA) circuit is presented. The circuit utilizes simple class AB voltage buffers to provide a non-slew-rate-limited performance with low standby power consumption. The OTA can be digitally programmed to maintain a constant settling time for different load capacitors without increasing the standby power consumption, Experimental results from a 1.2-/spl mu/m chip and comparisons with the regular folded cascode OTA circuit are given. The proposed circuit power consumption is found to be less than one third of a regular folded cascode OTA when driving a load capacitance of 35 pF. For the same power consumption level of 240 /spl mu/A, the new circuit achieves a slew rate more than 10 V//spl mu/s while the traditional folded cascode fails to settle.