Battery polarity insensitive integrated circuit amplifier

The present invention is generally directed to compact integrated circuit amplifiers designed to be powered by a single low-voltage battery and more specifically to compact high performance hearing aids designed to fit in the ear canal. A compact polarity-insensitive integrated circuit amplifier is described designed to be powered by a miniature low voltage battery of variable polarity. Low current, polarity corrected voltage sources are integrated into functional blocks to supply low current non-bidirectional elements and to provide a constant polarity bias to a substrate of CMOS circuits. Polarity corrected voltage sources are used to provide a polarity sensing function. The invention is embodied in a Class D amplifier which may comprise four n-channel MOSFET transistors arranged in an H-bridge configuration. Additional driver circuitry is described which increases the voltage of the pulse-width modulated input signal to the MOSFET transistors and also performs a pulse trimming function, which reduces parasitic crowbar currents in the amplifier output stage.