| 摘要 |
PURPOSE:To reduce a voltage error and to limit a current by providing a differential amplifier, a capacitor, a switch, etc. CONSTITUTION:The differential amplifier 4, the capacitor 5, the switch 1, etc., are provided. Then, an input terminal 3 is connected to the uninverted input terminal of the amplifier 4. Then, a capacitor 5 is interposed between the inverted input terminal of the amplifier 4 and a reference potential and an output terminal 6 is led out from the inverted input terminal. Further, a current source 7 and the switch 1 for charging the capacitor 5 are interposed in series between a power source VCC and the amplifier 4. The switch 1 is controlled with the output of the amplifier 4. Namely, the switch is off when Vin<=Vp and on when Vp<Vin. In this case, Vin is an input signal and Vp is the charging voltage of the capacitor 5. Consequently, when Vin>Vp, the switch 1 is turned on to charge the capacitor 5 with a current value I0. When Vin<=Vp, on the other hand, the current value is zero and the capacitor 5 is held at the voltage Vp. Therefore, the maximum peak voltage of the input signal is held at the terminal 6.
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