Cannot plot transient response (no graph/empty window)

Dear hikotoshi,

hikotoshi said:

Whenever I try to do a transient simulation of any circuit, I only get a black window, as seen below. DC and other simulations work fine. I've made a very simple inverter schematic as shown in the picture and I don't see any errors in the Spectre log. This problem occurs on any circuit, I've tried various. What could be the reason for this?

Did you check the CIW window for any issues? It sounds as if a netlist cannot be created -  possibly due to an invalid parameter in your transient input pulse. This will prevent spectre from simulating the circuit. In my limited experience, if a netlist cannot be generated, the response you describe is common. If there is no information in the CIW, You might try to enable the  +diagnose option to provide more information. If you have not done this before, some instructions are at Cadence On0line support at URL:

support.cadence.com/.../ArticleAttachmentPortal

It is a bit difficult for me to be certain on the issue as you have not included the netlist or input.scs file or the tools you are using...

Shawn

I have noticed the following in the CDS.log file:

net /INPUT selected but not highlighted

net /OUTPUT selected but not highlighted

No valid waveforms for plotting

No image saved: Possible reasons could be that none of the windows

or subwindows are visible or are non-empty.

Could this indicate the source of the problem? Both signals are set to plot & save.

I would advise you to contact customer support - I don't think it's a netlisting issue (since you wouldn't the dc sweep results either in that case). It does seem a bit strange, although you didn't mention anything about the versions used. It would be interesting to see if you can see the results in the results browser, and whether you can plot from there. However, I think the best thing would be to work with colleagues in support - a screen sharing session is likely to get the bottom of this quickly.

Andrew.

Dear hikotoshi,

hikotoshi said:

I've attached the input.scs. Tools are GF 22FDX-EXT.

input.scs:

Thank you for providing your input.scs file! This is quite helpful - to me anyway!

If you have not followed through with Andrew's suggestion to contact customer support, I think I may have found an issue that will preclude spectre from performing the transient simulation.

Examining your input.scs file, the input pulse statement to your inverter is defined as follows:

hikotoshi said:

V1 (INPUT 0) vsource type=pulse val0=0 val1=vdd period=1/F rise=0.1/F \
fall=0.1/F

However, it is missing the "width" attribute. Without the "width" atttribute, it is not clear how spectre can establish the pulse width. From the UNIX spectre -h vsource command, an example vpulse statement is provided below. Note the parameter "width" which is missing from the vpulse statement in your input.scs

Sample Instance Statement:
vpulse1 (1 0) vsource type=pulse val0=0 val1=5 period=100n rise=10n fall=10n width=40n

Did you specificy a width in the ADE setup GUI highlighted in Figure 1 hikotoshi?

Shawn

Figure 1

Dear hikotoshi,

hikotoshi said:

I've attached the input.scs. Tools are GF 22FDX-EXT.

input.scs:

Thank you for providing your input.scs file! This is quite helpful - to me anyway!

If you have not followed through with Andrew's suggestion to contact customer support, I think I may have found an issue that will preclude spectre from performing the transient simulation.

Examining your input.scs file, the input pulse statement to your inverter is defined as follows:

hikotoshi said:

V1 (INPUT 0) vsource type=pulse val0=0 val1=vdd period=1/F rise=0.1/F \
fall=0.1/F

However, it is missing the "width" attribute. Without the "width" atttribute, it is not clear how spectre can establish the pulse width. From the UNIX spectre -h vsource command, an example vpulse statement is provided below. Note the parameter "width" which is missing from the vpulse statement in your input.scs

Sample Instance Statement:
vpulse1 (1 0) vsource type=pulse val0=0 val1=5 period=100n rise=10n fall=10n width=40n

Did you specificy a width in the ADE setup GUI highlighted in Figure 1 hikotoshi?

Shawn

Figure 1

That still wouldn't cause only the dc sweep results to appear - it would most likely cause either a non-pulse waveform or an error. In practice though, if the width is omitted, it is inferred from the period and the rise/fall times (i.e. I think it's (period-rise-fall)/2). I just tried the netlist (with some made up models rather than looking for the right model files) and it runs OK, and I can plot INPUT and OUTPUT (from command line).

So that's not it...

The issue is very unlikely to be related to an error in the netlist - I'm struggling to think of what it might be though, since it doesn't sound like symptoms I've seen before...

Andrew

Yeah I did not but as Andrew suggested this was sadly not the cause of the issue, as even after specifying a width the graph is still blank. Thanks for the idea anyway.

Dear hikotoshi and Andrew,

Thank you, Andrew, for alerting me about the default width setting. I actually examined the analogLib reference for the independent pulse source to see if there was a default width value. From the reference manual, in Figure 2, it suggests there is not a default value - which is what prompted me to include myu comment - sorry! Perhaps, if you think it worth it, I can open a case to request the document I accessed might be updated to reflect the default value's existence?

hikotoshi said:

eah I did not but as Andrew suggested this was sadly not the cause of the issue, as even after specifying a width the graph is still blank. T

Rats!

Thank you anyway, hikotoshi, in any case for trying my suggestion!

hikotoshi said:

I do not have access to the license key required to unlock support capabilities. How do I go about contacting support in this case?

I think if you contact your IT or professor/teaching assistant (or whomever installs your Cadence tools), that individual can provide you with the license key.

Shawn

Figure 2

analogLib_ref_p400.pdf

Unknown said:

I can open a case to request the document I accessed might be updated to reflect the default value's existence?

It doesn't mention in "spectre -h vsource" that the width is calculated when period is given (if period is not given, then width defaults to infinity) - that's probably the first thing that should be fixed. By all means please do file a case on that.

To hikotoshi, I'd suggest first seeing if you can access the latest IC6.1.8 or ICADVM20.1 hotfix to see if that solves your problem (you still didn't mention which version you're using) - the latest is IC6.1.8.64b.500;16 (ISR 16) - i.e. with .16 at the end. If that doesn't work, follow Shawn's suggestion in order to contact support through you university link.

Andrew

Dear Andrew,

Andrew Beckett said:

By all means please do file a case on that.

I have filed case 46512013 as a minor case to document the issue.

https://support.cadence.com/apex/COSCaseDetailPage?CaseID=5003w00001T6fy4AAB&isNewCase=true

Shawn

Dear all,

I am someone who is having the same problem as this one.

Could you please let me know if this has been resolved and, if so, how?

Thank you

yysunj

Dear yysunj,

yysunj said:

I am someone who is having the same problem as this one.

Could you please let me know if this has been resolved and, if so, how?

There are several issues noted in this post (transient response waveforms not appearing in Viva, procuring a license key, updating your version of Cadence), which issue are experiencing?

If it is viewing the transient results, have your tried each of the suggestions in the post? Can you see the signal waveform(s) in the Results Browser? Can you plot the results of a DC analysis? What version of the Cadence tools are you using? What is the data format you are using to save the data? Are you sure the input.scs file contains a save statement for the signals you want to view?

Shawn

My issue is transient response waveforms not appearing in Viva.

1. I can not see the signal waveform in the results browser.

2. I can plot the results of a DC analysis.

3. Version of the Cadence tool which is I using is IC617.

4. I do not use data for simulation. I run the simulation through cadence virtuoso.

    What does the data format mean?

   Fig.1 is schematic of my simulation.

                   (Fig.1 The schematic of my simple circuit, resistance of R0 is 1k)

5. I wrote netlist using cadence virtuoso_schematic. I did not use input.scs file.

Additionally, If I run the transient analysis simulation, The message "No valid waveforms for plotting" appears in the CIW window.

What should I do to solve this problem?

Thank you

yysunj

Presumably you didn't save the signals in the transient analysis - if this was fundamentally broken, then we'd have many thousands of issues reported about this.

Please provide:

1. The input.scs from your transient simulation of the simple circuit above
2. (optionally) what is shown on the Outputs->Save All form
3. What you see in the results browser - provide a screenshot
4. Which sub-version you're using (you said IC6.1.7 - that's a whole range of releases that might be used - please show the sub-version that's in Help->About or what you get from typing getVersion(t) in the CIW).

Andrew

1. I did not import any input.scs file (ex. model card) in this simulation.

   Fig.1 is netlist of the simple circuit above.

                        (Fig.1 netlist of the simple circuit above)

2. Outputs ->Save All form is Fig.2

                            (Fig.2 Outputs ->Save All form)

3. What I see in the results browser is Fig.3

                                                                        (Fig.3 What I see in the results browser)

4. Sub-version I am using is IC 6.1.7-64b.500.12 (64-bit addresses).

Thank you

yysunj