Telephone interface circuit with impedance termination during call pauses
US5809134A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 29, 1996 |
| Grant date | Sep 15, 1998 |
| Priority date | — |
| Expiry date | May 29, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M1/738
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.