| US 7,609,817 B1 | ||
| Termination circuit for network interface unit | ||
| David E. Jones, Huntsville, Ala. (US) | ||
| Assigned to ADTRAN, Inc., Huntsville, Ala. (US) | ||
| Filed on Jul. 05, 2005, as Appl. No. 11/174,924. | ||
| Int. Cl. H04M 1/24 (2006.01); H04M 3/08 (2006.01); H04M 3/22 (2006.01); H04M 1/00 (2006.01) | ||
| U.S. Cl. 379—22.01 [379/29.01; 379/413.02] | 18 Claims |
| 1. A network interface unit, comprising:
an interface coupled to a first transmit line and a first receive line, the interface configured to receive a signal from
the first receive line;
a transformer coupled to the interface and a second transmit line;
circuitry operable in a test mode and a data mode, the circuitry configured to couple the received signal to the second transmit
line via a first path through the transformer while operating in the data mode, the circuitry further configured to disable
coupling of the signal to the second transmit line and couple the signal via an alternate path to the first transmit line
in the test mode; and
at least one resistive element coupled to the transformer and the interface and within the first path such that the signal
passes through the at least one resistive element between the transformer and the interface in the data mode,
wherein the circuitry is further configured to quietly terminate the second transmit line in the test mode by coupling the
at least one resistive element to a return path such that noise on the second transmit line is absorbed by the at least one
resistive element in the test mode.
|