Line interface circuit
US4656643A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 12, 1985 |
| Grant date | Apr 7, 1987 |
| Priority date | — |
| Expiry date | Aug 12, 2005 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L1/243
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A line interface circuit for connecting the transmit and receive ports of a transmitter to transmit lines (LX) and receive lines (LR), respectively. The interface circuit includes a transistorized differential amplifier provided with two load circuits comprising resistors and diodes connected in series, and logic control means for selectively switching power to either load circuit. One of the load circuits drives the transmit line (LX) while the other drives the receive ports of the transmitter. Switching the load circuits makes it possible to use the interface circuit either to drive the transmit line (LX) or to loop the output signal from the transmitter back to the receive input thereof, while loading the transmit line (LX) with its characteristic impedance.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.