Entropy

1
Entropy

• Veeraraghavan Ramamurthy

2
Simulation

• Logic Simulator
• True value simulation.
• Fault Simulator
• Simulation in presence of fault.

3
Algorithm

• Parse the netlist.
• Generate random input vectors.
• Obtain output of each level and propagate it to
  the primary output.

4
Compaction

• Generate a unique output list.
• Compare the bits output vectors to see the number
  of bits changed.
• Based on the percentage set either consider or
  discard the vector.

5
Results
Input Output Unique O/P Unique I/P Compact set 50 Compact set 10
1 0 0 0 0 0 1 0 1 1 0 1 0 1 0 1 1 0 1 0 0 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 1 1 1 0 0 0 0 0 0 1 1 1 0 0 0 0 0 1 1 1 1 1 0 0 0 0 0 0 1 0 1 0 0 0 1 0 1 0 0 0 0 0 0 1 0
6
Fault coverage comparison

• Random vectors
• read vector 1
• det faults 8 coverage 0.347826
• read vector 2
• det faults 14 coverage 0.608696
• read vector 3
• det faults 14 coverage 0.608696
• read vector 4
• det faults 14 coverage 0.608696
• read vector 5
• det faults 19 coverage 0.826087
• read vector 6
• det faults 20 coverage 0.869565
• read vector 7
• det faults 20 coverage 0.869565
• read vector 8
• det faults 20 coverage 0.869565

• Compact set
• For 50
• read vector 1
• det faults 8 coverage 0.347826
• read vector 2
• det faults 16 coverage 0.695652
• For 10
• read vector 1
• det faults 8 coverage 0.347826
• read vector 2
• det faults 14 coverage 0.608696
• read vector 3
• det faults 19 coverage 0.826087

7
Inference

• For a 3 bit input circuit maximum input possible
  is 8 vectors, which is compacted to 2 vectors if
  we use 50 as desired percentage and 3 vectors if
  10 is used.
• Total faults in the circuit is 23, random set
  detected 20 faults, compact set with 50 detected
  16 faults and compact set with 10 detected 19
  faults.
• The fault coverage for random input vectors is
  86.95 and for the compact set it is 69.56 for
  50 82.6 for 10 change.

8
Conclusion

• Fault coverage of the compact set was found to be
  less than the coverage of random vector set.
• Decrease in fault coverage is due to the
  algorithm used for compaction.