Frequency compensation for single-ended class AB operational amplifiers with fully-differential input stages

摘要

A class AB operational amplifier has first and second intermediate differential nodes respectively driving intermediate stage inverting and non-inverting amplifiers to produce a single-ended output voltage, which are provided with a frequency compensating feedback signal at a selected one of the first and second intermediate differential nodes, derived from the single-ended output of the operational amplifier subject to frequency compensation. The frequency compensating feedback signal is generated with the feedback circuitry. The feedback circuitry includes a compensation capacitor connected to the single-ended output and a current mirror circuit connected to the selected one of the first and second intermediate differential nodes of the operational amplifier.