| 摘要 |
A circuit and method for sensing in current mode when a telephone has been answered in a telephone system in which an answer is indicated when a dc component of a signal across a resistor exceeds a predetermined reference current. Currents sensed at the terminals of the resistor are combined to provide a third current that includes the dc component, without attenuation of the dc component. A filter separates the dc component from the third current so that the dc component can be compared to the reference current.
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