| 摘要 |
PURPOSE:To attain the normal communication at impedance change when a feeding circuit is connected to a two-wire side, by converting a signal voltage into a current, and performing the driving of signal from the input of 4-wire side of the hybrid transformer to the 2-wire side output by the converted current. CONSTITUTION:A change in a signal voltage inputted to a base of a transistor (TR)Q is a current change and this current is extracted as a current source from the collector. An output signal voltage of an operational amplifier OPA2 is converted into a current to drive the hybrid transformer T by the current. Even when a value of a resistor R12 is increased, the output current of a voltage/ current converting circuit C is applied sufficiently to the transformer T so as to drive normally the transformer T from the 4-wire side 4Wi, and an input signal of the 4Wi is transmitted to the 2-wire side 2W via the transformer T. Since the output impedance of the circuit C is high, the value of resistors R11, R12 is increased and the impedance viewed from the 2-wire side 2W is increased. |
