Increasing PRPG-based compression by delayed justification
AssigneeSynopsys, Inc.
InventorsPeter Wohl, John A. Waicukauski
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Abstract
An improved compression technique can increase PRPG-based compression by modifying test generation so that justification of certain decision nodes, called xheadlines, is delayed and merged with PRPG seed computation. Xheadlines are defined by gate modification restrictions, dynamic value considerations, and fanout allowance. Before mapping, the xheadlines can be preprocessed. This preprocessing can include transforming XOR xheadlines having shared inputs, augmenting AND/OR xheadlines, and reducing AND/OR xheadlines with common inputs. Mapping can include determining which xheadlines are satisfied by a current seed, which xheadlines can be satisfied by a future seed, and which xheadlines can opportunistically be satisfied by the current seed.
Claims23
A method of generating pseudo-random pattern generator (PRPG) seeds to increase scan compression, the method comprising:
- generating xheadlines for a circuit design, the xheadlines being decision nodes resulting from gate modification restrictions, dynamic value considerations, and fanout allowance;
- preprocessing the xheadlines;
- and
- mapping the xheadlines and any care bits, which are generated for non-xheadlines, to PRPG seeds.
Dependencies are inferred from the claim text.