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Simulators >> Circuit Simulators >> Include file in spectre
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Message started by sdv30 on May 27^th, 2016, 12:04am

Title: Include file in spectre
Post by sdv30 on May 27^th, 2016, 12:04am

I have a very simple question.
I am trying to include a file in spectre. I have the simplest setup possible.
I am using an empty netlist (only entry is simulator lang=spectre) and using a stimulus file, where I have only one include statement:
include "RefClk.txt"
The RefClk.txt file has a pwl voltage source in spectre syntax (simulator lang=spectre at the top of the file).
The issue is this: When I have a very low number of time/voltage pairs (e.g. 50) then the file is included and the simulation completes correctly.
When I try to include a more realistic pwl waveform with ~1000 time/voltage pairs, the simulations hangs.
Has anyone seen anything like that?
Thanks.

Title: Re: Include file in spectre
Post by sdv30 on May 27^th, 2016, 12:38am

Here are the ocean file used for the simulation and the log file:
-------------------
simulator('spectre)

; PARAMETERS OF THE SIMULATION:
tEnd= 1e-05
desVar("tEnd" tEnd)

;********************************************
; DESIGN SETUP:
design("./netlist")
stimulusFile("./stimulus" ?xlate nil)
temp(25)
analysis('tran ?stop "tEnd" ?errpreset "moderate")
;analysis('tran ?stop "tEnd" ?errpreset "conservative")
option( 'gmin 1e-14 'vabstol 1e-16 'reltol 1e-10 'iabstol 1e-16 )
resultsDir("./")
run()
results()
selectResults('tran)
outputs()

; REFERENCE CLOCK ZERO CROSSINGS:
ZCref=cross(v("Vref") 0.5 0 'rising)

out= outfile("ZCref.mat");
fprintf(out "%% Zero Crossings \n")
ocnPrint(?output out ?precision 20 ?numberNotation 'engineering ZCref )
close(out)

----------------------------------

COPYRIGHT © 1992-2015 CADENCE DESIGN SYSTEMS INC. ALL RIGHTS RESERVED.
© 1992-2015 UNIX SYSTEMS Laboratories INC.,
Reproduced with permission.

This Cadence Design Systems program and online documentation are
proprietary/confidential information and may be disclosed/used only
as authorized in a license agreement controlling such use and disclosure.

RESTRICTED RIGHTS NOTICE (SHORT FORM)
Use/reproduction/disclosure is subject to restriction
set forth at FAR 1252.227-19 or its equivalent.
Loading socket.cxt
Loading dal.cxt
Loading awv.cxt
Loading par.cxt
Loading alvs.cxt
Loading caa.cxt
Loading adexl.cxt
Loading te.cxt
Loading schHDL.cxt
Type ocnHelp() for help on OCEAN commands.
Look in .../tools/dfII/samples/artist/OCEAN for example
OCEAN scripts.
nil
ocean> *WARNING* (icLic-3) Could not get license Analog_Design_Environment_L
ocean> ocean> ocean> *INFO* (icLic-25) License Analog_Design_Environment_XL ("95210") was used to run ADE L.
Loading devCheck.cxt
Loading relXpert.cxt
spectre
1e-05
ocean> "1e-05"
ocean> ocean> ocean> ocean> INFO (OCN-6058): amap directory is missing in the netlist directory. Schematic names will not
get mapped to simulator names. Ensure that amap directory is present in the netlist
directory.
"./netlist"
ocean> ("./stimulus")
ocean> "25"
ocean> "moderate"
ocean> ocean> "1e-16"
ocean> "./"
ocean>

Title: Re: Include file in spectre
Post by Geoffrey_Coram on May 27^th, 2016, 6:48am

It sounds like you have a pwl source with a vector of t,v pairs like [0 v0 t1 v1 t2 v2 ...], and that vector is very long. Doesn't Spectre also allow you to specify a file for the t,v pairs? So the file would only have the t,v data (and the pwl source instance would be in a different file, such as the original netlist). I think the simulator may be better optimized for that case.

Title: Re: Include file in spectre
Post by sdv30 on May 27^th, 2016, 9:52am

Thank you for the reply. It turns out the simulation settings were too strict. If I relax them, I can get it to work.

Title: Re: Include file in spectre
Post by Ken Kundert on May 28^th, 2016, 11:17am

Always start with the default tolerances!

Also, it was a weird choice showing us the Ocean files. The problem was with the simulator. You should have shown us the simulation files.

-Ken

Title: Re: Include file in spectre
Post by AMS_ei on Jul 13^th, 2016, 6:20am

Hi,

There is a parameter in spectre: reltol.
You may please change its value to 0.001.

Hope this may help you.

Thank you.