An Enhanced Gain-Bandwidth Class-AB Miller op-amp With 23,800 MHz·pF/mW FOM, 11-16 Current Efficiency and Wide Range of Resistive and Capacitive Loads Driving Capability

Abstract

A compact power-efficient class-AB Miller op-amp is introduced. It uses a simple auxiliary circuit that enhances the op-amp’s gain-bandwidth product and helps to drive a wide range of capacitive and resistive loads with high static and dynamic current efficiency. Simple Miller compensation is used to obtain stability over a wide range of loading conditions. The op-amp’s simulation and experimental results in strong inversion with $15\mu \text{A}$ bias current and in sub-threshold with 250nA bias current are shown. Its performance is measured in terms of dynamic and static current efficiency figures of merit FOMCEDyn and FOMCEStat. and using the conventional small-signal figure of merit FOMSS. Experimental results of op-amps fabricated in a 130nm CMOS technology are shown that validate the proposed approach.

Keywords

• Analog integrated circuit
• class-AB amplifier
• Miller compensation
• voltage follower
• wide range load