DRIVING CIRCUIT FOR FIELD EFFECT TRANSISTORS

PURPOSE:To making a cutoff between the source and drain of an MOSFET at a high speed and thus switch the MOSFET speedily by the drain of the 1st MOSFET of the source of the 2nd MOSFET directly or through a diode. CONSTITUTION:One terminal of the 3rd winding n13 of a current transformer 14 is connected to the gate of a MOSFET15 and the source of a MOSFET8, and the other terminal of the 3rd winding is connected to the source of the MOSFET 15. The gate voltage of a MOSFET8 goes up to a high level (waveform D) at time t1. Further, a minus voltage with the negative polarity to the source of the MOSFET15 is applied to the gate between t1 and t2, so the MOSFET15 is off. Further, a negative-polarity pulse voltage can be applied to the gate of the MOSFET8 by turning on the MOSFET15 connected to the gate of the MOSFET 8, so the gate capacity of the MOSFET8 charged before time t3 is discharged speedily and the gate voltage of the MOSFET7 is lowered below a gate threshold value Vth in an extremely short time, thereby driving the MOSFET8 at a high speed.