Active impedance line feed circuit
US4514595A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 10, 1982 |
| Grant date | Apr 30, 1985 |
| Priority date | — |
| Expiry date | Jun 10, 2002 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M19/005
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A line circuit includes tip and ring voltage amplifiers each having an output resistively connected via tip and ring feed resistors to tip and ring leads in a telephone line. The tip and ring feed resistors have closely matched ohmic values, and are part of a resistance network which also includes first and second voltage dividers. The first voltage divider is connected in series between the output of the tip voltage amplifier and an end of the ring feed resistor remote from the output of the ring voltage amplifier, and includes a first voltage tap. The second voltage divider is connected in series between the output of the ring voltage amplifier and an end of the tip feed resistor remote from the output of the tip voltage amplifier, and includes a second voltage tap. A control circuit includes a differential input connected across the first and second voltage taps. In operation the control circuit causes the tip and ring voltage amplifiers to provide energizing direct current for the telephone line. Tip and ring feedback networks, connected across the respective tip and ring feed resistors, provide feedback signals to the tip and ring voltage amplifiers such that in operation comm…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.