| 摘要 |
PURPOSE:To facilitate IC-implementation and reduce an error in conversion by connecting the control electrode of a switching element to the output terminal of an arithmetic amplifying circuit, and averaging a rectification output signal by an LPF consisting of a resistance and a capacitor and obtaining a DC output signal. CONSTITUTION:An AC signal Vin to be converted into a DC signal, e.g. sine- wave signal is inputted to the uninverted input terminal of the arithmetic amplifying circuit 21. Further, the collector of an NPN transistor (TR) 22 is connected to an application point of a positive voltage VCC, the emitter of the TR22 is connected to a circuit point 23 for obtaining the half-wave rectified signal of the positive sine wave input signal, and the base is connected to the output of the circuit 21. A resistance 24 is interposed between the circuit point 23 and earth potential point, and the circuit point 23 is connected to the inverted input terminal of the circuit 21. Then, one terminal of the LPF27 consisting of the resistance 25 and capacitor 26 is connected to the circuit point 23. The time constant of the LPF27 is set much larger than the period of the input signal and a DC output signal voltage Vout showing the mean value of the half-wave rectified signal is obtained.
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