Patent
1983-03-07
1986-01-07
Dwyer, James L.
179170NC, H04M 174
Patent
active
045635471
ABSTRACT:
A switchable common mode reference circuit for tip conductor and ring conductor line feed amplifiers provides a tip-ring common mode feedback reference for loop-start operations and a common mode fixed bias for ground-start operations. The functioning of the line feed arrangement is enhanced by using separately-sensed tip and ring current signals to control the switching function and by switching the line feed amplifiers between a current source mode for loop-start operation and a voltage source mode for ground-start operation.
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patent: 4310725 (1982-01-01), Mehaffey
Laude, "A Monolithic Subscriber Line Interface Circuit", IEEE J. Solid-State Circuits, vol. SC-16, No. 4, pp. 266-270, 8/1981.
Pace, "A Monolithic Telephone Subscriber Loop Interface Circuit", IEEE J. Solid-State Circuits vol. SC-16, No. 4, pp. 270-278, 8/1981.
Aull et al., "A High Voltage IC for a Transformerless Trunk and Subscriber Line Interface", IEEE J. Solid-State Circuits, vol. SC-16, No. 4, pp. 261-266, 8/1981.
Davis et al., "A Hybrid Integrated Trunk and Subscriber Line Interface", IEEE International Solid-State Circuits Conference Digest of Technical Papers, pp. 204-205, 2/1982.
AT&T Bell Laboratories
Brendzel Henry T.
Dwyer James L.
Phelan Charles Scott
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