| 摘要 |
PURPOSE: To obtain the level control circuit not imposing any restriction onto the configuration of succeeding stages. CONSTITUTION: An emitter of a 1st transistor(TR) Q22 connects to a collector of a 2nd TR Q23 in series (TRs Q22, Q23 are of the same conduction type). The TRQ23 is in diode connection in terms of AC. An input signal source 11 connects to a connecting point between the emitter of the TRQ22 and the collector of the TRQ23 and a circuit 13 of a next stage is connected. A TRQ25 with equal common form to that of a TRQ21 of the first stage is provided to the circuit 13 of the next stage. A boas voltage equal to the TRQ21 is applied to the TRQ25. A TRQ28 detecting a difference between a collector current of the TRQ25 and a reference current is provided. The collector current of the TRQ22 is controlled by a level control signal. The detection output of the TRQ28 is fed to the TRQ23 as a control signal of its collector current. |
