What is the difference of setting up a delta of 0 , tolerance of 50.... (so 0:50)
no delta, tolerance of 100...... (so :100)
since in my case, a target appears if a delta is used.
follow up question:, how does constraint manager identifies a target net....?
Thanks in advance!!
In reply to oldmouldy:
Thanks again sir...
I wanted to clarify a couple things:
Setting the Delta:Tolerance field to 0.000mil:100.000mil means the longest net in the group could be 100mils longer than the target net and the shortest net in the group could be 100 mils shorter than the target. So across all the nets you could have a variance in length as much as 200mils before seeing a DRC. (+/-100mil)
Setting the Delta:Tolerance field to :100.000mil (blank Delta field) means that all the nets could have a variance in length as much as 100mils with no specific Target. This is sometimes harder to match the members and could cause you to overly lengthen the nets.
Hope this helps,Mike Catrambone
In reply to mcatramb91:
You might want to grab a copy of the following presentation from CDNLive in 2008:
8ICP12 : Demystifying Relative Propagation Delay Constraints
In reply to Dennis Nagle:
Thanks Mike and Dennis..
Finally figuring this out. Though sometimes I encounter this problem:
When I set delta:tolerance, let's say, 0:50 which also means :100 (pls correct me if i'm wrong), sometimes at 0:50 setting, constraint manager reflects red colors. I think, the problem with this is the random picking of the target.
In reply to jemarods:
You are correct. You would think that the results of using either 0:50 or :100 would be the same but the controlling factor is where the target ends up when using 0:50. Clicking on the Length column will sort the lengths so you can see which ones are out of range of the match and where the target should be set to. Right Mouse button on the Delta:Tolerance field to set the target to works the best, that is if you don't have a target net for the group to be matched to.
Good Luck,Mike Catrambone
Thanks again Mike,
Good day Dennis,
I cant access your file. I cant manage to login using my cadence account.