we are trying to follow the spectre RF noise-aware PLL sim flow. Using
MMSIM71 and IC5141_USR5(with latest hotfix), and the PLL is running at
2.5GHz. It goes well at the beginning, the divider ,CP and VCO model was extracted
sucessfully, though we can not view it since the model was encrypted.
We don't see much problem since it is a general PLL structure and the
flow is very straightfoward too. BTW, We set the ChargPump load voltage
(Vload) to 0.45~0.75.
The transient simulation also goes well
at first, untill the chargepump load voltage gradually reached 0.45V,
ie, the lower boundary of the voltage range that we set previously in CP
model extraction. Now the simulation become very slow, the simulation
step is in 0.01 fs. It takes 6 hours to simulate 3us. And after the
simulation run to 60us, the result psf data has become 65G bytes, which
is not possible to be handled by wavescan. Basides, my PLL will settle only after 100us.
For VCO CMI model, we set the "sampling point per second" to 50, and "inject jitter" to 100us.
Any clue any what's happening? Please kindly help, thanks a lot.
This question is probably best answered by submitting a Service Request via http://Sourcelink.cadence.com . There could be multiple issues going on here.
With regards to Wavescan not being able to plot spectre tran results....
Setting the environment variable setenv PSF_WRITE_CHUNK_MODE_ON truewill allow IC5.1.41 to read native spectre files that are larger than 2G.For some of the history on this, you may want to look at these two http://Sourcelink.cadence.com solutions:11352482 Why did the default output change from psfbin to sst2 in transient analysis?11264780 MMSIM 6.X and higher does not break up large tran.tran files
Sr. Staff Support AE, Global Customer Support
Cadence Design Systems, Inc.