Super Class-AB Recycling Folded Cascode OTA

A super class-AB version of the recycling folded cascode (RFC) operational transconductance amplifier (OTA) is proposed. The use of an adaptive bias circuit for the input differential pair provides dynamic current boosting and increased gain-bandwidth product (GBW). Moreover, use of local common-mode feedback (LCMFB) at the load of the differential pair further improves these performance parameters and provides high current efficiency. Measurement results of a test chip prototype fabricated in a 0.5-μm CMOS process show an increase in slew rate and GBW by a factor of 34 and 3, respectively, versus the conventional RFC OTA using the same supply voltage and bias currents. Overhead in other performance metrics is small.