| 摘要 |
PURPOSE:To ensure the high-sensitivity and high-speed transmission of pulses by supplying the output of the operational amplifier to the collector of the photo transistor via the feedback circuit and thus to keep the collector-emitter voltage constant. CONSTITUTION:When photo transistor TrT1 receives the light, the current flows from operational amplifier Q1 through resistance R1 to cause the voltage drop across R1. At the same time, Q1 amplifies its input voltage so that the voltage of the reverse input terminal may be equal to reference voltage VREF. Accordingly, TrT1 supplies the change of the optical current to the reverse input terminal of Q1 in the form of the voltage change. And Q1 functions to keep the collector voltage of TrT1 constant, thus realizing the high-speed pulse transmission. |
