| 摘要 |
PURPOSE:To ensure the independent setting for the working level and the lower limit level of the dynamic range, by using plural numbers of transistors and diodes among which the same electrodes are connected to each other. CONSTITUTION:The electrodes of (n) units of transistors TRQ1-Qn are connected to each other; and also the electrodes are also connected to each other for (m) units of diodes D1-Dm respectively. Then input terminal P1 is connected to the base of TRQ1-Qn; and the emitters of TRQ1-Qn and the cathodes of diodes D1-Dm are grounded via resistance R1. At the same time, the collectors of TRQ1-Qn are connected to power source VCC; and the anodes of diodes D1-Dm are connected to source VCC via resistance R2 as well as to output terminal P2. With such constitution of the circuit, the lower limit level of the dynamic range is decided by the resistance ratio R2/R1. And the working level can be varied by the number ratio n/m of the units connected in parallel. As a result, the independent setting is possible for the lower limit level and the working level each. |
