Patent ID: 7498751

Claim:
A lamp driving apparatus to illuminate a lamp comprising: a power circuit that provides alternating current to said lamp; a control circuit that extracts current and frequency information from the power circuit; and a control signal that controls the power circuit; wherein said power circuit comprises: a power transistor for passing current, and a transformer comprising a primary winding and a secondary winding, wherein said primary winding is used as a load for said power transistor and said secondary winding is used to transfer energy to the lamp; and wherein said control circuit comprises: a current controller that extracts the current of a power amplifier and couples with a PWM (pulse width modulation) circuit, and a periodic waveform generator that couples with said PWM circuit and a frequency modification circuit, wherein said frequency modification circuit extracts the frequency information from said power amplifier, and said power amplifier further comprising said power transistor and said primary winding used as a load.