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Tessent parallel presim fail, but serial pass

Question asked by dft_engineer on Jan 4, 2018
Latest reply on Jan 8, 2018 by richa

Hi all,


i get a case which stuck at scan pattern presim parallel  fail, but serial run pass,

The following are the  waveform &  fail pattern ATPG good results.


1. parallel presim cell A got mismatch in pink area,(sim = 0, exp=1)


2. fail pattern ATPG : From this pic , we can see the D pin of cell A  is 100, but simulated value is 000, and mismatch come from cell B,

webwxgetmsgimg (1).jpg


3. serial presim:

we can see serial result and ATPG is match(cell B get 1 after shift done)

webwxgetmsgimg (2).jpg


How can I debug the parallel presim mismatch?

thank you.