| 摘要 |
PURPOSE:To eliminate DC bias dependability peculiar to a semiconductor in case of circuit integration by applying a constant-current bias to a part for receiving a signal by DC direct-coupling. CONSTITUTION:Current mirror circuits Ac, Bc receive through a resistance R1 a signal from a subscriber's terminal generated in terminals A, B, and the output is brought to current-voltage conversion by an emitter resistance RV signal converting transistors QTN, QTP, and outputted to voltage output terminals VOA, VOB. The bases of TRs QTN, QTP are connected to reference power sources VX, VY. Also, the collectors of TRs QTN, QTP are connected to current output terminals IOA, IOB, and a current proportional to voltage between the terminals A, B and a battery or a ground is outputted. In this case, constant-current sources IA, IB are connected to the emitters of the TRs QTN, QTP. In this way, DC bias dependability peculiar to a semiconductor by an integration can be eliminated, a load current is varied for a time, and it is utilized in case of circuit integration in which the allowance of characteristic variation is strict. |
