1. An isolated amplifier for use in a system having an earth ground comprising: a main amplifier having first and second inputs for receiving signals, said main amplifier including means for receiving at least one power supply voltage and having a circuit ground electrically isolated from said earth ground; means for sensing a common mode voltage received by said first and second inputs and having an output for providing a compensation voltage representative of said common mode voltage; and a capacitance to said earth ground for receiving said compensation voltage, said means for sensing and said capacitance causing said at least one power supply voltage to track said common mode voltage.