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How can I avoid the following error running an aps-pss with mmsim 10.1?
Error found by spectre during periodic steady state analysis `pss'. ERROR: ZERO DIAG reordering in Matrix factor ERROR: ZERO DIAG reordering in Matrix factor ERROR: ZERO DIAG reordering in Matrix factor ERROR: ZERO DIAG reordering in Matrix factor ERROR: ZERO DIAG reordering in Matrix factor
I would suggest you log a service request for this issue. It looks like CCR 941065 which is to do with the beat frequency calculated by the GUI not matching the actual beat frequency due to rounding error and thus getting an inaccurate match (probably looking at the analysis statements in the input.scs would reveal this). You could try typing "autofund=yes" into the Additional Parameters field at the bottom of the PSS options form - but this is very much a wild guess - it may not be this problem at all. Without seeing the data, it's very hard to be sure (there are very few reports of this precise error message).
So that's why a service request makes sense - we can then take a more detailed look at the data.
In reply to Andrew Beckett:
Thank you Andrew!
Can I attach your answer to the service request?
In reply to Aldo2:
Hello Mr. Beckett,
I have experienced the same problems as Aldo:
When using the spectre-pss everything works fine, when I switch to aps-pss I will get the error message:
ERROR: ZERO DIAG...
(Error message after finishing the third iteration.)
Has anything happened since Aldo posted the request?
(The autofund=yes did not fix the problem.)
****************************************************Periodic Steady-State Analysis `pss': fund = 200 MHz****************************************************Trying `homotopy = gmin' for initial conditions.Zero diagonal found in Jacobian at `I1125.I81:out_flow' and `I1125.out1'.Zero diagonal found in Jacobian at `I1125.I81:out_flow' and `I1125.out1'.Zero diagonal found in Jacobian at `I1125.I81:out_flow' and `I1125.out1'.Zero diagonal found in Jacobian at `I1125.I81:out_flow' and `I1125.out1'.Zero diagonal found in Jacobian at `I1125.I81:out_flow' and `I1125.out1'.Trying `homotopy = source' for initial conditions.Trying `homotopy = dptran' for initial conditions..Zero diagonal found in Jacobian at `net035' and `net035'.Zero diagonal found in Jacobian at `net035' and `net035'.Zero diagonal found in Jacobian at `net035' and `net035'.
I think the problem is hidden somewhere in the above lines, which aps shows, but spectre does not (copied from outputLog).
In reply to matzowicz:
Customer Support Director - Analog/Mixed-Signal/RF AEs
Cadence Design Systems, Inc.
In reply to Tawna:
thanks for the quick reply.
(I'm using MMSIM 10.1)
I think I was imprecise formulating the problem:
The above warnings arised with aps but not with spectre when trying to find the dc-solution. Both simulators find a DC-operating point and start to simulate.
I have used tstab so that the signals can settle.
After the second iteration, the pss aborts.
pss: time = 4.625 ns (72.5 %), step = 650.1 fs (13 m%) pss: time = 4.876 ns (77.5 %), step = 1.407 ps (28.1 m%) pss: time = 5.128 ns (82.6 %), step = 3.777 ps (75.5 m%) pss: time = 5.376 ns (87.5 %), step = 2.209 ps (44.2 m%) pss: time = 5.625 ns (92.5 %), step = 3.092 ps (61.8 m%) pss: time = 5.876 ns (97.5 %), step = 964.7 fs (19.3 m%)Conv norm = 69e+03, max dV(I1151.hold) = -2 V, took 55.62 s.Error found by spectre during periodic steady state analysis `pss'. ERROR: ZERO DIAG reordering in Matrix factor...(plenty of repetitions here) ERROR: ZERO DIAG reordering in Matrix factorAnalysis `pss' was terminated prematurely due to an error.
I think that there is a problem when the simulator compares the new simulation results (2nd run) with the old ones (from the 1st run).
The pss runs perfectly fine with spectre, but it's too slow. (I have to use the pss, otherwise the results will be to imprecise.)
A wonderful day,
It's still possible that the problems are related - since the solution that Tawna mentioned had similar symptoms and was also a difference between APS and standard spectre. I would suggest trying the hotfix that is mentioned in the solution and if that doesn't work, please log a service request as she suggested.