| 摘要 |
PURPOSE:To reduce the size of the subscriber circuit and highly integrate it by removing a large-sized component such as a coil from the subscriber circuit of an electronic exchange which supplies a speech current to a two-wire subscriber line and connects with a transmission and reception line on the other side and arranging one terminating resistor for both two wires and four wires. CONSTITUTION:A reception line 31 is divided into two lines of the subscriber line 30 and integrated circuit elements such as a transistor and an operational amplifier are used to supply DC electric power through the line terminating resistor 14; and the speech current is amplified and an inverting amplifier circuit 12 is inserted into one of the two wires in series. On the other hand, the two wires of the subscriber line 30 are connected to a differential amplifier circuit 15 and an input signal is outputted to a transmission line 32. A hybrid circuit 11 is arranged between those reception line 31 and transmission line 32. |
