US Patent 7561404 Biased-MOSFET active bridge

A transistor active bridge circuit (100) provides operation and protection for devices from the effects of battery polarity reversal. The circuit includes first and second field-effect transistors (102, 104) of a first channel type, and third and fourth field-effect transistors (106, 108) of a second channel type that is different from the first channel type. A set of voltage dividers (110, 112, 114, 116, 118, 120, 122, 124) and voltage clamping devices (126, 128, 130, 132) permit the circuit (100) to efficiently operate over a wider range of input voltages, without potential damage to the field-effect transistors.