| 摘要 |
<p>A circuit is disclosed for limiting current leakage in a signal path in a current leakage barrier (200) between telephone line (202) and user equipment sides (204) of the telecommunications device. The resistive elements (214) are coupled on the telephone line side to tip and ring conductors of a telephone line pair. A differential amplifier circuit (232), comprising a high-impedance operational amplifier disposed on the user equipment side, has its inputs coupled to the resistive elements (214). The differential amplifier circuit (232) is operative to generate an analog output signal proportional to the potential difference between the ring and tip conductors. The output signal may then be amplified and used as input by one or more circuits associated with signaling functions of the telephone line pair, such as a line-in-use detection or line connected circuit.</p> |
