Patent ID: 7205821

Claim:
A drive circuit for a switching circuit, comprising: first and second gate control outputs for connection to gates of respective first and second insulated gate transistors; first and second gate drivers connected to the first and second gate control outputs respectively for driving the respective gates to switch the first and second insulated gate transistors on and off alternately; monitoring circuitry for monitoring voltages on first and second monitor points and hence a state of the first and second insulated gate transistors respectively, the first monitor point being one of the gate of the first insulated gate transistor and a switch node between first and second insulated gate transistors and the second monitor point being the gate of the second insulated gate transistor; wherein the drive circuit is arranged: to drive the second gate driver to switch off the second insulated gate transistor and then after a first controllable delay to drive the first gate driver to switch on the first insulated gate transistor; to compare a first time that the voltage on the first monitor point passes a first predetermined voltage and a second time that the voltage on the second monitor point passes a second predetermined voltage; and to decrease the first controllable delay if the second time is before the first time and to increase the first controllable delay if the second time is after the first time.