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A Technique for Path Sensitizing During Circuit Testing

IP.com Disclosure Number: IPCOM000037659D
Original Publication Date: 1989-May-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Godoy, HC: AUTHOR

Abstract

To test a complex electronic circuit today, it is frequently advisable to begin with a check of a single "block", unit or device that may be embedded in such circuit. The technique to achieve this test begins with assuming a number of ways a failure can occur and the probable results on surrounding components in the circuit. An output path from that block is needed to check these assumptions.

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A Technique for Path Sensitizing During Circuit Testing

To test a complex electronic circuit today, it is frequently advisable to begin with a check of a single "block", unit or device that may be embedded in such circuit. The technique to achieve this test begins with assuming a number of ways a failure can occur and the probable results on surrounding components in the circuit. An output path from that block is needed to check these assumptions.

Normally, to sensitize a path from one point in a circuit to another, all inputs along that path must be set to a value that is non-controlling, and this has been found to be good, except when reconvergence is involved. "Reconvergence" is a condition that involves an output from a test block that is connected to different parts of the circuit which connects back to affect the block output later on in the circuit. Therefore, if reconvergence occurs at some point along the path selected for use in the test, it may be necessary to sensitize both paths simultaneously.

The technique is as follows:

1.) A trace character is propagated from the block being tested.

2.) A backtrace is begun from a selected point, and as each block is "backed into" during the backtrace procedure, all of its inputs except the one containing the trace character are added to a request list at a non-con trolling value. 3.) When more than one input to a test block is found to have the trace character, this is indicative that reconvergence is involved, ...