Custom IC Design - Recent Threads

try_fast_op with SpectreX

SL20260319720 — Mon, 24 Aug 2026 02:18:32 GMT

Hi,

Is it possible to disable try_fast_op when simulating transient with SpectreX? I set have the option "no" selected under ADE Explorer -> simulation -> Options -> analog -> try_fast_op (see attached picture). After netlisting, I see the text "try_fast_op=no" as part of simulatorOptions. However, the transient simulation usually spend significant amount of time at the stage "Trying Fast DC 0 for initial condition." It appears that Spectre is still trying to do fast DC for initial condition.

Regards,

Su Lim

Closing Pegasus results viewer causes hierarchy return during Pegasus DRC

ED202602057731 — Thu, 13 Aug 2026 17:46:56 GMT

Situation: open a layout block in VirtuosoXl and descend one or more levels. run Pegasus DRC on the sub-block. When you close the DRC debugging tool, the hierarchy will snap back to the top-level that you opened. I'm sure this is a setting and it is just an annoyance, but if anyone has a solution, I would be grateful

Measure across sweep in MC and get results to yield table for each MC point

Aboubakr — Thu, 13 Aug 2026 17:22:11 GMT

Hi,

I’m wondering if there is a way to get a measurement of eval type “sweeps” in a MC run to measure across only the sweep variables but not MC sweeps, so that I get the result for each MC point still.

and of there is a way to select which variable to measure across, I know there is measureAcross() function but it doesn’t seem to what the name implies.

this discussion touched on the same topic near the end, and Andrew mentioned that there was no way to do that 3 years ago, any updates today ?

[mention:15ed758d2b0f49a5b08a30b0c446ca61:46448885d0e64133bbfbf0cd7b0fd6f7]

thank you,

Aboubakr

VIVA reload: black window

Martinsh — Mon, 10 Aug 2026 07:40:59 GMT

IC251 isr6. When transicient simulation is runing, plot signal works well, but if reload from VIVA menu File->Reload, all signal waveforms on the result window are removed. How to solve this problem?

RE: VIVA reload: black window

Andrew Beckett — Mon, 10 Aug 2026 09:34:43 GMT

Please contact customer support.

Andrew

RE: psf format different when simulation is run from ADE or in command line

Andrew Beckett — Thu, 06 Aug 2026 09:07:42 GMT

The simplest is probably to use the context. Functions that access current (eg IDC, IT) would map the terminal, and those which access voltage would map the net. That said, I’ve not really thought this through properly because I’ve never looked into actually doing this…

psf format different when simulation is run from ADE or in command line

kkdesbois — Tue, 04 Aug 2026 09:21:17 GMT

Hello,
When I run a simulation from ADE, I can see in VIVA a wave for each net, even if the simulation is a DC without sweep.

If I run the simulation file runSimulation from the directory netlist created by ADE, in VIVA each net is a scalar now and can not be plotted

Any reason for that? What makes the creation of wave rather than a scalar?
Laurent.

RE: psf format different when simulation is run from ADE or in command line

kkdesbois — Thu, 06 Aug 2026 07:13:50 GMT

Thanks Andrew.
I didn't see your answer (email warning does not work for every reply).
I was also using this function. I also need its sister function, asiMapTerminalName, when the expression is like : (IDC "/amp_top/amp_low/MPampDiff0/s")

How can I tell whether the last argument of the expression refers to a net or a terminal?
I was thinking of getting the lib/cell from the hierarchy (I don't know yet how to do that) and checking whether the last expression argument (in the previous example : s) is a member of the list returned by almGetTerminalList.

Is there a more elegant or straightforward method?

RE: psf format different when simulation is run from ADE or in command line

Andrew Beckett — Tue, 04 Aug 2026 14:51:00 GMT

Not really. The trouble is that the mapping could be complex if the name happened to use a spectre reserved word, but in general you could use:

asiMapNetName("/the/path/to/maestro/results/maestro/Interactive.10/2/TRAN_ONLY/psf" list("/diffOut"))

(it copes with the "psf" dir or the one above - the "data" dir).

That's just for the net name part - it doesn't transform the entire expression.

Andrew

RE: psf format different when simulation is run from ADE or in command line

kkdesbois — Tue, 04 Aug 2026 14:16:37 GMT

[quote userid="508632" url="~/cadence_technology_forums/f/custom-ic-design/66240/psf-format-different-when-simulation-is-run-from-ade-or-in-command-line/1409085"]So I need to adapt the ADE output expressions to support netlist names.[/quote]

By the way, Is there a function to transform the ADE output expressions written as schematic name to expression written as netlist name?

RE: psf format different when simulation is run from ADE or in command line

kkdesbois — Tue, 04 Aug 2026 12:40:48 GMT

ok. Thanks for the explanation. I really thought that VDC() returned nil because it's a scalar in psf and not a wave.
So I need to adapt the ADE output expressions to support netlist names.

Laurent.

RE: psf format different when simulation is run from ADE or in command line

Andrew Beckett — Tue, 04 Aug 2026 12:34:24 GMT

That expression should work if VDC() returns a scalar (it certainly can do that) It's just subtracting two scalar values and then taking the absolute value - that should be OK. The issues is that VDC() is returning nil. That's because the argument to the VDC has been given as a schematic name rather than a netlist name (it begins with a "/" and could use "/" as the hierarchy separator). For this to work, it needs the runObjFile in the point psf directory to point to the netlist directory, where it uses the mapping data to map from schematic names to netlist names.

If you change the expression to (abs (difference (VDC "VOUT") (VDC "VREF"))) then it would work fine (the leading slash is removed).

Andrew

RE: psf format different when simulation is run from ADE or in command line

kkdesbois — Tue, 04 Aug 2026 12:10:49 GMT

ok, clear. I understand now the utility of this runObjFile.

Why do I want a psf with waves?
I save ADE outputs (ocean expressions) and would like to apply them, thanks to an ocean script, to a psf created by a spectre unix command.
example :
This ADE expression :
is saved in an ocean script as : offset=(abs (difference (VDC "/VOUT") (VDC "/VREF")))
If this this ocean expression is applied on a psf created from spectre unix command (i.e, containing scalar if the DC analysis has no sweep), it returns the following error :
*Error* difference: can't handle (nil - nil)

RE: psf format different when simulation is run from ADE or in command line

Andrew Beckett — Tue, 04 Aug 2026 11:54:01 GMT

It's not really that the nets are saved as waves for psf/testName/psf. What happens is that for the psf/testName/psf dir, ADE creates a runObjFile which collates the individual point results together as a family, and hence when opening that you get waveforms instead (because there might be more than one point simulated and even with a single point it's a waveform of one point).

You'd have to surround the analyses statements in spectre with some kind of sweep to achieve the same thing:

tempSweep sweep param=temp values=[27] {
dcOp dc write="spectre.dc" maxiters=150 maxsteps=10000 annotate=status
dcOpInfo info what=oppoint where=rawfile
}

This is a sweep of one point. I'm not sure why you would want to do this though?

Andrew

RE: psf format different when simulation is run from ADE or in command line

kkdesbois — Tue, 04 Aug 2026 11:46:03 GMT

Thanks Andrew.
While you were answering, I realized my mistake and misunderstanding.

ExporerRun0/psf/testName/psf : the nets are saved as waves
ExporerRun0/1/testName/psf : the nets are saved as scalars

And of course when I RMB->Open Terminal and launch runSimulation, I re-create this ExporerRun0/1/testName/psf (i.e, scalar).

Now my questions are:
How is the ExporerRun0/psf/testName/psf created?
Is it possible (with a spectre argument or option) to make the ExporerRun0/1/testName/psf contain waves rather than scalar?

RE: psf format different when simulation is run from ADE or in command line

Andrew Beckett — Tue, 04 Aug 2026 10:38:33 GMT

Laurent,

This is because in the top one you are using the results browser for the entire set of simulations (you might only be running one, but ADE could allow multiple runs because of sweeps or corners). In other words, you're looking at the psf/testName/psf dir rather than (e.g. 1/testName/psf dir - the number being one of the points). If you go over one of the output cells in the ADE results and do Right Mouse->Results Browser it would open the specific point only and then you should see what you are seeing in the bottom ViVA.

Hope that makes sense.

Andrew

RE: Add MOM license key Error: TSMC PDK Tool Error : No setting file

Andrew Beckett — Tue, 04 Aug 2026 06:33:04 GMT

You should contact TSMC (or your distributor if you don’t work directly with TSMC) about this. Not really something that can be dealt with in a public forum.

Andrew

Add MOM license key Error: TSMC PDK Tool Error : No setting file

GZ20260415257 — Tue, 04 Aug 2026 06:24:48 GMT

Hi Community,

I was trying use layout MOM cap and found license needed. And I tried to add MOM license as tutorial, error occured.

As the picture shows, "no setting file" error reported. I have no ideal about this error and cannot find any solution.

May I got some help?

Unable to select Accuracy Defaults in spectre 25.1

VIRAJ PANCHAL — Sun, 02 Aug 2026 07:02:24 GMT

Hello community,

I've upgraded my spectre version from 23.1 to 25.1.

When I create a maestro view and add the new transient analysis, so in the analysis I can't able to select Accuracy Defaults (conservation, moderate and liberal)..!!

So my question, is that a spectre 25.1 tool issue or something else..? (In spectre 23.1 I can able to select Accuracy Defaults.)

Look into in below snapshot of spectre 25.1. The Accuracy Defaults is disable kind of thing.

- Viraj.

RE: Unable to select Accuracy Defaults in spectre 25.1

VIRAJ PANCHAL — Tue, 04 Aug 2026 04:16:00 GMT

Got it, thanks for this information Andrew.

Global Girds cannot be displayed.

JH202504237643 — Tue, 04 Aug 2026 03:21:20 GMT

Hello,

After I update the PDK，Global Girds cannot be displayed.

The Global Grids option is checked.

pdk version: v1.2_2p2a2.

Thanks,

Han

Auto Via in Edit-in-Place with metals on higher levels

PK202501238151 — Mon, 03 Aug 2026 09:36:33 GMT

Hello,

I am using auto-via to generate vias between overlapping metals. I often work in edit-in-place, which means that some of the metals might be on higher hierarchy levels. These are apparently not considered when using auto vias. Is there a way of getting this to work?

RE: Auto Via in Edit-in-Place with metals on higher levels

Andrew Beckett — Mon, 03 Aug 2026 10:56:49 GMT

There is an enhancement request for this (Cadence Change Request #2458518) - one challenge of course is that when you edit-in-place and then place vias taking into account shapes outside of the descendent hierarchy of the cell you are editing, you may end up placing vias where other occurrences of the same cell have different metal above them. Sometimes that will be fine, but that's the reason why it's not done out of the box.

You could use this SKILL code (could be called from a bind key). It will prompt you to enter points for a box to do the auto-via within:

procedure(CCFgenViaInEIP(@optional (win hiGetCurrentWindow()))
  letseq(
    (
      (cv geGetEditCellView(win))
      (tf techGetTechFile(cv))
      (topCV geGetWindowCellView(win))
      (constraintGroupName cstGetDefaultConstraintGroupName(cv "Via"))
      (constraintGroup cstFindConstraintGroupIn(tf constraintGroupName))
      (viaOpts viaGetViaOptions(constraintGroup))
      ; compute transformation from top to EIP cellView
      ; could use dbInvertTransform(dbGetInstTransform(geGetInstHierPath(win))))
      ; but  this was only added in IC25.1 ISR3
      (dbu cv~>DBUPerUU)
      (xform list(win~>d2eTransX/dbu:win~>d2eTransY/dbu win~>d2eTransOrient))
      box topVias
    )
    box=enterBox(?prompts list("Enter area for via creation"))
    ; create the vias in the top cellView and then move them into the
    ; EIP cellView
    topVias=viaGenerateViasInArea(topCV box viaOpts ?startLevel 0 ?stopLevel 32)
    unless(cv==topCV
      foreach(via topVias
        dbMoveFig(via cv xform)
      )
    )
    t
  )
)

Andrew

RE: Unable to select Accuracy Defaults in spectre 25.1

Andrew Beckett — Sun, 02 Aug 2026 07:30:31 GMT

Viraj,

From IC25.1 the default is Spectre X (set on the High Performance Options form under the Setup menu). Usually the accuracy settings are then controlled using the performance level (cx, ax, mx, lx, vx). This can be overridden if needed via the preset override (although I wouldn’t do that for errpreset), or you can change the high performance mode back to APS or Spectre if needed.

Andrew

How to measure phase margin through deepprobe.?

VIRAJ PANCHAL — Sat, 25 Jul 2026 15:38:36 GMT

Hello community,

I am doing the verification of one block. I want to measure the phase margin(PM) though stability analysis.

I know the method to measure the phase(i.e connect iprobe in feedback path). But my this circuit is complex, so I want to measure the PM from top level testbench so I am using the deepprobe and cds_thru to connect the signal.

but I am unable to measure PM. In maestro view I got error message in PM expression.

So my question is that is this a right method to measure PM. if it is right then which probe should I select in stability form.?