Patent ID: 7432663

Claim:
A circuit for igniting a high intensity discharge lamp, the circuit comprising: first and second DC input terminals adapted for coupling to a substantially direct current (DC) rail voltage; first and second AC input terminals adapted for coupling to an alternating output voltage of a DC-to-AC inverter; first and second output terminals that provide a lamp ignition voltage and that are adapted for coupling to a high intensity discharge (HID) lamp, wherein the second output terminal is coupled to the second AC input terminal; a charging circuit coupled between the first and second DC input terminals; a transformer comprising a primary winding and a secondary winding, wherein the primary winding is coupled between the charging circuit and a first node, and the secondary winding is coupled between the first AC input terminal and the first output terminal; a metal-oxide semiconductor field-effect transistor (MOSFET) coupled between the first node and the second DC input terminal; a clamping diode coupled between the first node and the first DC input terminal; and wherein the circuit is operable to provide a voltage boost to the lamp ignition voltage upon deactivation of the MOSFET while current is still flowing in the MOSFET and wherein the lamp ignition voltage has a positive peak that is not significantly reduced by parasitic characteristics of the circuit.