| 摘要 |
An improved impedance generator circuit, for use with two-wire transmission systems of the type encountered in telephony, is adapted to be interfaced with the wires and operates in a manner to effectively generate a desired positive or negative impedance across the wires. The impedance generator includes a current source, and generates a positive impedance by drawing from the wires all of the current that would otherwise be required by the positive impedance, or a negative impedance by providing on the wires all of the current that would otherwise be provided by the negative impedance, in response to a metallic voltage applied across the wires by a signal source. At the same time, the impedance generator provides common mode rejection to longitudinal voltages on the wires.
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