| 摘要 |
PURPOSE:To prevent destruction of a transistor (TR) by providing a parallel circuit composing of a resistor and a diode between a drive power source of a gate of the 2nd TRs of cascode connection and the gate and selecting the polarity of diode in the turning-on direction of the TR. CONSTITUTION:A bipolar (BPT) TR Q1 and a field effect TR (FET) Q2 are connected in series to constitute a composite TR. A parallel circuit composing of a resistor R2 an da diode D1 is added between a drive power source EG of the FET Q2 and the gate G and the diode D1 is provided in a polarity conducting a gate current IG 1 to turn on the FET Q2. In turning on the FET Q2, a sufficient gate current IG1 is applied by bringing a switching signal voltage eG to 'H' level. Then, in turning off the FET Q2, when the switching signal voltage eG is brought into 'L', a gate current IG2 suppressed properly flows from the gate G to the drive power supply EG. Thus, the voltage induced in a stray inductance L1 is limited below the breakdown voltage of the FET Q2. |
