| 摘要 |
PURPOSE:To input both TTL and analog inputs and to obtain the same output by adopting direct coupling to an input signal for a binary signal such as TTL and adopting capacitor coupling for an analog signal so as to change over each constant current source simply. CONSTITUTION:Transistors (TRs) 23, 24 constitute a differential pair and resistors 25, 26 are connected respectively to emitters to ensure the linearity of the amplifier. Further, the resistors 25, 26 are connected to a TR 27 and a resistor 28 constituting a constant current source and applies amplification with a good linearity. Moreover, TRs 34, 35 constitute a differential pair, and since no emitter resistor is employed, switching operation is applied to the TTL input and waveform shaping is applied to the input waveform whose waveform is unsharpened. Thus, in inputting directly a signal having a large amplitude as the TTL, the waveform shaping is applied and an analog output is outputted through capacitor coupling for a signal input with a small amplitude such as an analog input.
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