Reset tree skew

I disagree with Frankz. Throughout the various release of Encounter I've been promised that it can do this well, but I still don't like the results. From some trials I did I found that the buffer tree inserted by Encounter is not optimized. Encounter takes care for transition, but it uses more buffers and has larger delay than when creating it with CTS.

After I run CTS I remove the buffer trees created on large fanout nets (resets, shift_enable, etc.) and use the CTS engine to create the optimized tree. You can see my little procedure below. You have to prepare a file, a list and decide on the delay/skew/transition values.

deleteBufferTree -selNetFile remove_buffertree.txt -allowCreateAssign
foreach elem $HIGH_FANOUT_LIST {
  bufferTreeSynthesis -bufList $tree_buffers -fixedBuf -fixedNet \
                      -maxDelay $tree_maxDelay \
                      -maxSkew  $tree_maxSkew \
                      -maxTran  $tree_maxTran \
                      -prefix ${elem}_tree \
                      -nets $elem
 }

I disagree with Frankz. Throughout the various release of Encounter I've been promised that it can do this well, but I still don't like the results. From some trials I did I found that the buffer tree inserted by Encounter is not optimized. Encounter takes care for transition, but it uses more buffers and has larger delay than when creating it with CTS.

After I run CTS I remove the buffer trees created on large fanout nets (resets, shift_enable, etc.) and use the CTS engine to create the optimized tree. You can see my little procedure below. You have to prepare a file, a list and decide on the delay/skew/transition values.

deleteBufferTree -selNetFile remove_buffertree.txt -allowCreateAssign
foreach elem $HIGH_FANOUT_LIST {
  bufferTreeSynthesis -bufList $tree_buffers -fixedBuf -fixedNet \
                      -maxDelay $tree_maxDelay \
                      -maxSkew  $tree_maxSkew \
                      -maxTran  $tree_maxTran \
                      -prefix ${elem}_tree \
                      -nets $elem
 }