Subscriber line interface circuit
US4866767A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 16, 1988 |
| Grant date | Sep 12, 1989 |
| Priority date | — |
| Expiry date | Aug 16, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M19/005
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
The subscriber line interface circuit comprises subscriber nodes, reception nodes and transmission nodes, a power feeding unit, adders, impedance elements, an inverting amplifier, and a feedback element. The subscriber nodes are coupled to a subscriber terminal via a subscriber line, and the reception and transmission nodes are coupled to an exchange via a reception line and a transmission line, respectively. The feeding unit supplied a DC current to the terminal and controls the current. The first adder adds the voltage between the subscriber nodes and the voltage from the reception node. The first impedance element has an impedance corresponding to a real-number multiplication of the impedance between the subscriber nodes, and is applied with the output voltage of the first adder. The amplifier is given with the output of the first impedance element. The second impedance element, inserted in the feedback path of the amplifier, has an impedance corresponding to a real-number multiplication of the impedances of the subscriber line and the terminal. The feedback element supplies, to the feeding unit, a signal corresponding to the current flowing through the first impedance element a…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.