| 摘要 |
PURPOSE:To reduce the voltage applied between the collector and the emitter of a PNP transistor (Tr) by using a Zener diode to divide the voltage applied between said collector and emitter. CONSTITUTION:An input terminal P1 of one side is connected to an earth terminal GND connected with a positive electrode of a DC power supply 6; while an input terminal P2 of the other side is connected to a non-reverse input terminal of an operational amplifier 1. The reverse input terminal of the amplifier 1 is grounded via a feedback resistance 7, and the output terminal of the amplifier 1 is connected to the base of a PNPTr2 having its emitter containing a feedback resistance 9 and grounded. The collector of the Tr2 is connected to a negative electrode of the power supply 6 via and in series to a Zener diode 30 and a negative resistance 10. An input signal ei impressed to an input terminal of the amplifier 1 against the terminal GND. The output of the amplifier 1 undergoes DC amplification by the Tr2. Here the diode 30 is inserted to a collector circuit of the Tr2. Therefore only the DC voltage is divided without giving any effect to the amplified signal by the constant voltage characteristics of the diode 30. Thus the voltage applied between the collector and the emitter of the Tr2 can be reduced.
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