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Browse Prior Art Database

Full Duplex Line Driver

IP.com Disclosure Number: IPCOM000077989D
Original Publication Date: 1972-Oct-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Lautier, A: AUTHOR [+2]

Abstract

This terminal facilities circuitry affords full-duplex transmission over a two wire line between terminal stations spaced apart.

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Full Duplex Line Driver

This terminal facilities circuitry affords full-duplex transmission over a two wire line between terminal stations spaced apart.

Both terminal circuitry T1 and T2 are substantially identical. Each one comprises a signal source V feeding two operational amplifiers A1 and A2, the noninverting inputs of which are grounded. The inverting input of A1 is connected to the signal source V through series connected resistors R and R1. The feedback loop of A1 is through the primary winding of a 1/1 line transformer TR. The inverting input of A2 is connected to the same signal source V through R and R2 in series. Both resistance R1 and R2 are equal in value. The feedback loop of A2 comprises an impedance Z' equivalent to the impedance of the feedback loop of amplifier A1. An impedance E1 equivalent to the internal impedance of terminal station T2, is placed in parallel on the secondary winding of transformer TR. A load impedance RL is connected between the output terminals of amplifiers A1 and A2.

During a transmit operation of T1, voltage source V drives both amplifiers A1 and A2; a current flows through TR primary winding, therefore, a receive operation a current proportional to the signal received by terminal T1 flows through R1 and can be sensed. Both transmit and receive operations may occur simultaneously, therefore providing full-duplex operation.

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