High performance amplifier circuits using separate power supplies

摘要

The present invention is an apparatus and method to provide a high supply rejection and a full rail-to-rail output swing in an amplifier circuit. A first stage generates a first output. The first stage is powered by a second supply. A second stage is coupled to the first stage to generate an amplifier output. The second stage is powered by a first supply. The first and second supplies are different in regulation mode. By making the second supply a low noise supply, the power supply noise amplified by the first stage is minimized, with the voltage gain of the second stage regaining the rail-to-rail swing lost by the first stage due to the regulator supplying very low noise power to the first stage.