| 摘要 |
<p>The balancing bridge circuit (11) is provided between a four-wire circuit and a two-wire circuit, to provide a thin-type balancing bridge circuit having satisfactory transmission characteristics and a MODEM having this balancing bridge circuit built therein. The transmitting terminals (E, F) of the four-wire circuit and the connection points (A, C) of the balancing bridge circuit are connected together through the photo-coupler (12). The receiving terminals (G, H) of the four-wire circuit and the connection points (B, D) of the balancing bridge circuit are connected together through the photo-coupler (13). The terminals (J, K) of the two-wire circuit are connected to the connection points (C, D) of the balancing bridge circuit. By the presence of the compact photo-couplers (12, 13), it is possible to ground the transmitting terminal (F) and the receiving terminal (H) together. Common-mode noise reaching the terminals (J, K) is not transmitted to the receiving terminals (G, F). <IMAGE></p> |
