I am designing a VCDL for DLL. But the PSS analysis is not converging. I am trying to change "reltol" value but @ very begining of simulation it is showing a warning
'reltol' is not a valid parameter for an instance of `pss' . Ignored
Can anyone tell me if I can change reltol value at all in PSS analysis?
reltol is an options parameter ("spectre -h options") not an analysis specific parameter. You can use errpreset to affect the reltol, but if you want to set reltol you'd do:
myOpts options reltol=1e-5
In reply to Andrew Beckett:
Ya, its working. But I am not able to increase it from 1e-03(default value) though am able to decrease it....
In reply to Amessi:
Setting errpreset=liberal on the PSS is as loose as we allow. It really doesn't make sense to loosen the tolerances too much with PSS as typically you want a reasonable dynamic range in whatever you're simulating with PSS.
Did you try that?
I am using
PSS is converging for 500MHz but fails in 800MHz
May I ask you were do you set the above parameters, if you are using Cadence Virtuoso?
In reply to HamidKhatibi:
It can be added in test bench manually