Patent ID: 7259632

Claim:
A method for cascading a first amplifier stage and a second amplifier stage, each amplifier stage being coupled to a power source providing a power supply voltage and a power supply reference point, each amplifier stage including an output terminal providing an output current and an output voltage relative to its own power supply reference point, the output terminal of the second amplifier stage to be coupled to drive a load, the method comprising: coupling the output terminal of the first amplifier stage to the power supply reference point of the second amplifier stage; modulating the power supply reference point of the second amplifier stage using the output current of the first amplifier stage; and generating a final output voltage at the output terminal of the second amplifier stage having a first voltage value relative to the power supply reference point of the first amplifier stage, the first voltage value being the sum of the output voltage of the first amplifier stage relative to its own power supply reference point and the output voltage of the second amplifier stage relative to its own power supply reference point.