| 摘要 |
PURPOSE:To improve the frequency characteristic and to reduce power consumption by providing a transistor (TR) of emitter follower connection to a base of a power TR and receiving an input signal from a base terminal thereof and providing a voltage holding circuit. CONSTITUTION:The voltage holding circuit 10 is connected to a connecting point Pc between a collector of a TR Q2 forming a differential pair and a base of a power amplifier TR Q3, and the voltage holding circuit 10 consists of an NPN TR Q4 whose collector/emitter path is connected between a power terminal Vcc and the connecting point Pc and whose base is connected to a control signal input terminal 11. Moreover, a constant current source circuit 12 supplying a constant current from the power terminal Vcc is connected to the connecting point Pc, a PNP TR Q5 of emitter-follower connection whose collector is connected to a ground terminal is provided and the base is connected to a signal input terminal 13. Thus, the sample-and-hold circuit having a wide dynamic range and excellent frequency characteristic is obtained.
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