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Simulators >> Circuit Simulators >> Problem with HSPICE
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Message started by pgbackup on Mar 16^th, 2009, 9:00am

Title: Problem with HSPICE
Post by pgbackup on Mar 16^th, 2009, 9:00am

Hi all,

I'm running the latest HSPICE release from Synopsys: hspice-C-2009.03.
I have a model for a carbon nanotube transistor developed by a university. I am trying to simulate a basic inverter. I run my the simulation as follows: 'hspice inv.sp >run.log'.

I'm getting an error. Upon examining run.log, I see the following errors:

**error** the output variable used in the algebraic equation of element
7:gbtbt does not exist.

**error** the output variable used in the algebraic equation of element
7:g_qtotal does not exist.

**error** the output variable used in the algebraic equation of element
7:g_qchannel does not exist.

When I dig in closely to the model, the above errors result from these lines (in cnfet.lib):

GCNT Drain Source CUR='JFET(V(Drain,Source),photon,V(phib,Sub))'
GBTBT Drain Source CUR='J_btbt(V(Drain,Source),I(GCNT),V(phib,Sub))'
G_Qtotal Vdrain phib CUR='charge_channel(V(Vdrain),V(Vgate),V(Vsource),V(VsubM),V(phib,Sub))'
G_Qchannel phib Sub CUR='charge_total(V(Vdrain),V(Vsource),V(phib,Sub))'
GCNT Source Drain CUR='JFET(V(Vdrain,Vsource),photon,V(phib,Sub))'
GBTBT Source Drain CUR='J_btbt(V(Vdrain,Vsource),I(GCNT),V(phib,Sub))'

The current version of HSPICE doesn't like the fact that CUR is not defined as a variable? Since I'm not an expert in SPICE, I'm not sure how I can fix this problem.

I was able to simulate this circuit fine in and older HSPICE release without any problems.

Can someone tell me how I fix the above problem? I tried adding .PARAM CUR to the cnfet.lib file but that didn't fix it.

I'm also attaching the complete files if anyone wants to see

Thanks for any ideas.

Regards

Title: Re: Problem with HSPICE
Post by pgbackup on Mar 16^th, 2009, 9:02am

The files are attached. Its cnfet.zip

Title: Re: Problem with HSPICE
Post by Geoffrey_Coram on Mar 16^th, 2009, 2:28pm

It looks like it's not complaining about GCNT, which also uses CUR, so either you didn't put in all the errors (don't know why you put in 3 if not all), or else CUR isn't the problem.

Is J_btbt defined properly? I see this in the lib file you uploaded:

.PARAM J_btbt(Vds,Ids,phib)='coeffj*kT*(Jbtbt_sub_1(Vds,Ids)*Tbtbt1(Vds,phib) + \\
Jbtbt_sub_2(Vds,Ids)*Tbtbt2(Vds,phib))'

Maybe the new version doesn't like th \\ newline inside the 'quotes' ?

Title: Re: Problem with HSPICE
Post by pgbackup on Mar 16^th, 2009, 7:28pm

Hi Geoffrey,

Thanks for taking the time to respond.

I agree it is not complaining about GCNT. run.log contains all the errors that hspice lists outs.

Since I have not written the model, I am not sure if the syntax is correct. However, I was able to simulate using this library on a 2007 version of HSPICE. I have contacted the developers to see if they can help fix this issue.

I looked at the "\\" and tried removing it but to not avail. There were also two spaces " +" before the plus sign. But that didn't seem to work either.

Thanks

Title: Re: Problem with HSPICE
Post by spiceoracle on Apr 13^th, 2009, 1:43pm

I'm not sure what the problem is.

I've run your testcase using HSPICE C-2009.03 on a number of different machines. HSPICE runs successfully and does not give the error messages that you have seen. The only difference I see is that the machine that I used that is similar to the one that you used is the OS version.

Title: Re: Problem with HSPICE
Post by pgbackup on Apr 30^th, 2009, 9:53pm

Hi,

Thanks for taking the time to try the test case out. I was able to solve this problem a few back. I was running Fedora 10 and the problem was happening. This OS is not supported by Synopsys. I switched to Red Hat Enterprise Linux 4 (which is supported) and the problem was gone. I guess it must have been some string processing/parsing libraries causing the strange errors.

On the other hand, I guess when EDA vendors means they only support a particular OS, they really mean it :)