| 摘要 |
PURPOSE:To eliminate decrease in characteristic impedance due to Early effect and the superposition of a ripple on the output of a constant voltage circuit and to facilitate the integration of the circuit by providing the constant voltage circuit connected between a constant voltage output terminal and a common terminal, an electronic switch connected between the connection point of a constant current circuit and a discharge preventing circuit and the common terminal, and a bias circuit which controls the opening and closure of the discharge preventing circuit. CONSTITUTION:The constant current circuit 21, discharge preventing circuit 23, and constant voltage circuit 24 are connected in series between the input terminal (P6) for power supply and signal input and output and the common terminal (P7), and the constant voltage output terminal (P8) is connected to the connection point of the discharge preventing circuit 23 and constant voltage circuit 24. Further, the electronic switch 22 which has the function of a comparison control circuit 25 is connected between the constant current circuit 21 and common terminal (P7). Further, the bias circuit 26 is connected between the constant current circuit 21 and discharge preventing circuit 23. Then, the characteristic impedance viewed from from the terminal is prevented from decreasing owing to the Early effect of the transistor of the constant current circuit 21 and the transistor of the discharge preventing circuit is prevented from operating as an opposite-directional transistor.
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