Telephonic communications – Substation or terminal circuitry – Amplifying
Patent
1989-10-24
1990-08-28
Ng, Jin F.
Telephonic communications
Substation or terminal circuitry
Amplifying
379413, 379387, H04M 100
Patent
active
049532073
ABSTRACT:
An electronic telephone set which includes first and second connection points for a telephone line and a transmission circuit having a send output stage including a first transistor whose first main electrode is coupled to the first connection point by means of a first resistor. The telephone set includes a supply circuit for peripheral circuits. The supply circuit has a first output terminal coupled to the first main electrode of the first transistor and has a second transistor whose first main electrode is coupled to the second connection point and whose second main electrode is coupled to the second output terminal of the supply circuit. This circuit includes an operational amplifier whose output is coupled to the gate electrode of the second transistor. the set also includes a first voltage source connected between the first main electrode of the second transistor and a first input of the operational amplifier. In order to make a more efficient use of the available line current in long telephone lines, the second main electrode of the first transistor is coupled to the second input of the operational amplifier and, by means of a second resistor, to the second connection point.
REFERENCES:
patent: 4748664 (1988-05-01), Blomley
Jouen Philippe B. E.
Sijbers Petrus J. M.
Van Dongen Frederik
Franzblau Bernard
Hugustus Jhancy
Ng Jin F.
U.S. Philips Corporation
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