Patent ID: 8084952

Claim:
An electronic ballast for a gas discharge lamp comprising: a power supply circuit comprising a buck inductor; a rectifying circuit coupled to the power supply circuit to provide a rectified buck inductor signal responsive to voltage across the buck inductor, wherein the rectified buck inductor signal has associated first and second low signal zones, and further wherein each of the first and second low signal zones corresponds to distinct power conditions of the buck inductor; a compensator circuit coupled to the power supply circuit and to the rectifying circuit, and operable to provide a compensation signal when the rectified buck inductor signal is in the first low signal zone; a reference source operable to provide a reference signal; a comparing circuit coupled to the reference source, to the rectifying circuit, and to the compensator circuit to receive the reference signal, the rectified buck inductor signal, and the compensation signal; the comparing circuit operable to provide a comparing circuit output signal that is modulated by comparisons between the reference signal, the rectified buck inductor signal, and the compensation signal; and the power supply circuit further comprising an input coupled to receive the comparing circuit output signal, the power supply circuit being responsive to the comparing circuit output signal to control the operation of the lamp.