Browse Prior Art Database

Active Terminator

IP.com Disclosure Number: IPCOM000082460D
Original Publication Date: 1974-Dec-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Barish, AE: AUTHOR [+2]

Abstract

The device depicted in Fig. 1 may be used in place of a standard matched passive terminator where power considerations are of prime importance. Operation of the Device is as follows:

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Active Terminator

The device depicted in Fig. 1 may be used in place of a standard matched passive terminator where power considerations are of prime importance. Operation of the Device is as follows:

For approximately the first 50% of the incident transition (positive or negative) both diodes are in the off state (high impedance), creating a reflection which is in phase and equal to one-half of the incident wave. For the second half of the incident waveform, either the diode connected to V up or the diode connected to V down turns on (positive and negative transitions, respectively).

The series resistance of the diode created through the physical structure (see Figs. 2 and 3) produces an out-of-phase reflection, equal to approximately 40% of the incident wave. Hence, the net reflection sent to the driver is a 10% "inphase" reflection. This is precisely what is needed to return the driver to its low-current DC state. This reflection does not cause excessive ringing as would the full reflection, which would be received without the use of the active terminator.

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