Patent ID: 6686729
Filing Date: 2004-02-03
Classification: H02M,H03K,Y02B

Abstract:
In a voltage converter comprising a semiconductor switch coupled to an inductor, a first capacitor and a rectifier, the semiconductor switch having a gate and being driven between ON and OFF states from first and second voltage sources by a control circuit, a circuit for improving switching efficiency of the semiconductor switch comprising:a second capacitor; a first transmission gate coupled between the second capacitor and the gate of the semiconductor switch, wherein the control circuit is coupled to the first transmission gate and generates a control signal to turn ON the first transmission gate when the control circuit isolates the semiconductor switch from the first and second voltage sources, turns OFF the first transmission gate before the control circuit drives the semiconductor switch to a second one of the ON and OFF states,turns on the first transmission gate after the first control circuit isolates the semiconductor switch from the first and second voltage sources and turns OFF the first transmission gate before driving the semiconductor switch from the second of the ON and OFF states, to the first of the ON and OFF states, whereby a portion of charge stored on a parasitic capacitance of the gate of the semiconductor switch is stored in the second capacitor and reused to partially drive the semiconductor switch from the first of the ON and OFF states to the second one of the ON and OFF states.