PURPOSE: To obtain impedance matching between a device and a load, by forming two closed loops from the middle point of a winding via a resistance and providing a switching circuit to each closed loop and turning on the switch circuits provided in these closed loops when no pulse signal exists.
CONSTITUTION: When "0" of a bipolar signal is transmitted, both the switch circuits 22 and 23 are opened with the switch circuits 24 and 25 closed respectively. In this case, two closed loops are realized at an output transformer of a circuit 20. The resistance of a resistance circuit 13 for matching is connected to the middle point of the transformer of the circuit 20 and does not contribute to a matching action of impedance. Thus the two windings of the transformer of the circuit 20 are terminated by the matching resistances of the resistance circuits 26 and 27 respectively to realize the matching of impedance with the load ZL of a circuit 15.
GOTOUDA TAKAO
TAKADA AKIHIKO
NOGUCHI HIROYUKI
KOMIYA HISHIICHI
SASAGAWA MASAAKI
NIPPON TELEGRAPH & TELEPHONE