Patent ID: 8264160

Claim:
An electronic ballast, comprising: a rectifier circuit, having a pair of input terminals for receiving an ac (alternating current) input voltage and a pair of output terminals for outputting a dc (direct current) voltage, wherein a first output terminal of the rectifier circuit is coupled to a first node and a second output terminal of the rectifier circuit is coupled to a second node; a first capacitor, having two ends coupled to the first node and the second node, respectively; an inverter, having a first terminal, a second terminal and a third terminal, wherein the first terminal of the inverter is coupled to the first node, the second terminal of the inverter is coupled to the second node; an inductor, having a first end coupled to the third terminal of the inverter and a second end for coupling a first terminal of a lamp; a second capacitor, having two ends for coupling a second terminal and a third terminal of the lamp, respectively; a third capacitor, having a second end coupled to a third node, wherein the third node is further for coupling a fourth terminal of the lamp; and a diode, having a first end coupled to the third node; wherein when a voltage of the first node falls below a cross voltage of the third capacitor, the diode discharges the third capacitor.