| 摘要 |
PURPOSE:To attain high speed for the converting operation by using a circuit to be clamped by an MOSFET to prevent saturation of a bipolar transistor (TR). CONSTITUTION:An emitter follower circuit is formed by connecting a base of an NPN TRQ1 to an input terminal 1 and connecting its emitter 3 to a negative power supply via a resistor R1. A drain of a P-channel MOSFET80 whose base is grounded is connected to the emitter 3 and the source of the FET80 is connected to a base 42 of a PNP TRQ2. The gate of the FET80 and the collector of the Q2 are connected and used as an output terminal 41 to form a circuit preventing the saturation of the Q2. The connecting point is connected to the terminal 41 and also connected to the negative power supply via a load resistor R4. Moreover, the emitter of the Q2 is grounded via a low resistance R3, and then a resistor R5 is connected between the negative power supply and the emitter, through which an operating voltage is impressed to the Q2. Thus, a signal amplitude converting cirucit operated in high speed is obtained in this way. |
