Patent ID: 8125156

Claim:
A circuit arrangement for operating at least one high-pressure discharge lamp comprising: four switches in a full-bridge arrangement, a first and a second switch forming the first half-bridge arm, and a third and a fourth switch forming the second half-bridge arm, at least two terminals for coupling the high-pressure discharge lamp between the midpoint of the first and the second half-bridge arms, at least two terminals for supplying the circuit arrangement with a dc voltage signal and a drive circuit for driving the four switches, wherein the drive circuit is designed to provide drive signals, for the four switches, whose clock pulse is swept between a first and a second frequency, and whose pulse width and/or phase is modulated with a prescribable third frequency, and wherein the drive circuit comprises a PWM module whose clock input is coupled to a first source for the clock pulse swept between the first and the second frequencies, and whose modulation input is coupled to a second source for the signal at the third frequency.