| 摘要 |
PURPOSE:To prevent noise level deterioration due to a temperature rise by inserting a constant voltage element at the base of a gate transistor (TR). CONSTITUTION:The parallel connection body of diodes D1 and D2 is connected to the base of the gate TRQ1; the diode D1 is in the forward direction and the diode D2 is in the backward direction. The diode D2 uses, for example, an aluminum Schottky diode and its forward voltage is smaller than that of the TRQ1. The collector of a control TRQ2 is connected to the common connection point of the D1 and D2 on the side opposite to the base of the TRQ1. When the TRQ1 is off, an inequality I holds where VFD is the forward voltage of the diodes. In this case, the left side member of the inequality I never becomes smaller than the right side member even at high temperature, so the noise level at high temperature does not increase. The diode D2 discharges base accumulated charges of the Q1 when the Q1 turns off and an inequality II holds. |
