Telephonic communications – Substation or terminal circuitry – Impedance matching or line equalizing
Patent
1996-05-29
1998-09-15
Zele, Krista
Telephonic communications
Substation or terminal circuitry
Impedance matching or line equalizing
379377, 379387, 379398, 379418, H04M 100
Patent
active
058091343
ABSTRACT:
A telephone interface circuit with impedance termination during call pauses, comprising first and second terminals to connect to a telephone line and a line termination branch connected to the first terminal across a decoupling capacitor, and to the second terminal. The line termination branch includes an intersection node, a first switch and a first impedance resistor between the first terminal and the intersection node, and a second switch and a second impedance resistor between the second terminal and the intersection node. The intersection node is connected to ground across a third switch. The first switch, the second switch, and the third switch are controlled by a control unit by first, second and third control lines, respectively. The telephone interface circuit further comprises a ring signal detector that is connected to a microprocessor unit capable of activating the control unit in an interval in which the circuit must be terminated for CLID (Calling Line IDentification) transmission.
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European Search Report from European Patent Application 95830224.2, filed May 30, 1995.
Antonini Carlo
Consiglio Pietro
Sanit-Surin Jacques M.
STMicroelectronics S.r.l.
Zele Krista
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