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Passive Networks for State Change Monitoring

IP.com Disclosure Number: IPCOM000061890D
Original Publication Date: 1986-Jul-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Mizzi, JV: AUTHOR

Abstract

This analog circuit can be used to monitor the change of state of a large number n of binary lines more efficiently than can be done using binary circuits. In a typical application, a network of some 300 binary lines must be monitored. If one or more lines change state, the entire pattern on the network is stored (or collected").

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Passive Networks for State Change Monitoring

This analog circuit can be used to monitor the change of state of a large number n of binary lines more efficiently than can be done using binary circuits. In a typical application, a network of some 300 binary lines must be monitored. If one or more lines change state, the entire pattern on the network is stored (or collected").

As shown in the figure, each of the n lines is monitored by a circuit consisting of three components (a capacitor and two diodes). Any current flowing through a capacitor is segregated by direction (via the diodes) to flow through either R1 or R2. The difference in voltage between point 1 and point 2 (V12) is monitored by an analog caparator. A change of state in one or more lines in either direction will cause a unidirectional voltage difference V12. The capacitors should be small values to limit crosstalk, and the R1C (or R2C) time constant should be smaller than the fastest signal repetition rate being monitored. Then, the comparator will detect distinct spikes in the same direction for each state change episode, i.e., either single or multiple line changes in any direction.

If the RC time constant is made long relative to the repetition rate of the signals, the magnitude of V12 would measure of the "average activity" on the network.

Disclosed anonymously.

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