Patent ID: 6867645

Claim:
An apparatus to generate a pulse width modulated voltage signal, said apparatus comprising: a DC voltage source; a first switching circuit comprising a first switch and a second switch configured in a series circuit, said first switching circuit electrically coupled in parallel with said DC voltage source; a second switching circuit comprising a third switch and a fourth switch configured in a series circuit, said second switching circuit electrically coupled in parallel with said DC voltage source; an output comprising a first electrical junction coupling said first switch with said second switch and a second electrical junction coupling said third switch with said fourth switch; said second switching circuit configured to maintain said third switch in a conduction state while said fourth switch is maintained in a non-conducting state so as to establish a first polarity of an output signal; said first switching circuit configured to switch said first switch and said second switch at a modulation frequency; said first switching circuit configured to maintain said second switch in a conducting state while maintaining said first switch in a non-conducting state so as to establish a second polarity of said output signal, said second polarity being the reverse polarity of said first polarity; said second switching circuit configured to switch said third switch and said fourth switch at said modulation frequency; and a microprocessor electrically coupled to the first and second switching circuits, wherein the microprocessor generates control signals according to a selected pulse width modulation scheme to control the timing and operation of the first and second switching circuits.