PSRR improvement technique for amplifiers with Miller capacitor

A simple circuit technique is presented for improving poor midband power supply rejection ratio (PSRR) of single ended amplifiers that use Miller capacitance to set the location of the dominant pole. The principle of the technique is to create an additional parallel signal path from the power supply to the output, which cancels the dominating unity gain signal path through the output stage and Miller capacitor above the dominant pole frequency. Simulation results of a two-stage amplifier show that more than a 20dB improvement in the midband PSRR is obtainable as compared with an amplifier without the suggested circuit.