| 摘要 |
PURPOSE:To switch a high voltage and a large current with a low drive power without using an element having a specific characteristic by applying the switching drive of a composite semiconductor device via the gate of an auxiliary FET. CONSTITUTION:A high dielectric strength auxiliary bipolar transister (BPT) Q11 and a low dielectric strength auxiliary FET Q12A in cascode connection are used, and the switching operation for the Q11, Q12A is applied while the base and the emitter of a main BPTQ1 are connected in series with the main circuit of the FETs Q11, Q12A. The collector current of the FET Q11 is a base current of the FET Q1, the value becomse sufficiently smaller than the main circuit current, the loss of the base region of the FET Q11 is kept to a small value and no special transistor is used for FET Q11. Then the switching of the composite semiconductor device is applied via the gate of the FET Q12A and its drive current is made small in power. |
