Telephonic communications – Subscriber line or transmission line interface
Patent
1997-10-30
2000-09-19
Isen, Forester W.
Telephonic communications
Subscriber line or transmission line interface
379377, 379413, H04M 900
Patent
active
061223670
ABSTRACT:
In a subscriber line interface circuit, a device applies to a line, associated with the line interface circuit, a substantially constant line current of a first predetermined value for line voltages up to a first voltage having an absolute value which, by a predetermined amount, is lower than the supply voltage of the line interface circuit. For line voltages between the first voltage and a second voltage having an absolute value which, by a predetermined amount, is higher than the first voltage, a line current which is inversely proportional to the line voltage and of a value between said first predetermined value and a second predetermined, lower value is applied to the line. For line voltages between the second voltage and a third voltage having an absolute value which, by a predetermined amount, is higher than the second voltage, a substantially constant line current of the second predetermined value is applied to the line. For line currents of lower value than said second predetermined value, the line voltage is maintained substantially constant at the third voltage.
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Pieters, Jozef et al., "A Monolithic 70-V Subscriber Line Interface Circuit", IEEE Journal of Solid-State Circuits, vol. SC-21, No. 2, pp. 252-258, Apr. 1986.
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Eriksson Hans
Larsson Elisabeth
Isen Forester W.
Saint-Surin Jacques M.
Telefonaktiebolaget LM Ericsson
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