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desVar interdependencies in maestro

Ymmen

hi,

In maestro view (ADE Explorer) I have defined desVar "Vin1" which is a function of another desVar "Pin1".

Pin1 = -40

Vin1 = sqrt(2*50*10**((Pin1-30)/10))

In HB analysis when I sweep Pin1 from -40 to 0, I see Pin1 sweeping but Vin1 evaluates 3.16e-3 which corresponds to Pin1=-40. In other words, Vin1 does not change its value with the sweep. This problem is seen in maestro. ADEL didn't had this issue. In picture attached I have added netlist and maestro view. 

Is there a way we can enable desVar interdependency so that if one of them is swept, the other updates automatically?

virtuoso: IC6.1.8-64b.500.20

spectre: 19.1.0.373.isr7

Fullscreen 0714.netlist.txt Download 
// Point Netlist Generated on: Feb 24 09:19:28 2022
// Generated for: spectre
// Design Netlist Generated on: Feb 24 09:19:28 2022
// Design library name: NUECES_ygoel
// Design cell name: HB_plots
// Design view name: schematic
simulator lang=spectre
global 0
parameters Pin1=-40 frf1=1G Vin1=3.16227766016838e-3

// Library name: NUECES_ygoel
// Cell name: HB_plots
// View name: schematic
PORT1 (net2 0) port r=50 type=sine
PORT0 (net1 0) port r=50 type=sine freq=frf1 ampl=Vin1
R0 (net1 net2) resistor r=1m
simulatorOptions options psfversion="1.4.0" reltol=1e-3 vabstol=1e-6 \
    iabstol=1e-12 temp=27 tnom=27 homotopy=all scalem=1.0 scale=1.0 \
    gmin=1e-12 rforce=1 maxnotes=5 maxwarns=5 digits=5 cols=80 pivrel=1e-3 \
    sensfile="../psf/sens.output" dochecklimit=yes checklimitdest=both \
    bsimsoi_va=yes disk_check_thresh=1.048576e+08 
sweephb  sweep  param=Pin1  start=-40  stop=0  step=20  {
  hb  hb  tstab=0  oversample=[1]  fundfreqs=[(frf1)]  maxharms=[5]
+   errpreset=moderate  annotate=status

}

modelParameter info what=models where=rawfile
element info what=inst where=rawfile
outputParameter info what=output where=rawfile
designParamVals info what=parameters where=rawfile
primitives info what=primitives where=rawfile
subckts info what=subckts where=rawfile
asserts info what=assert where=rawfile
saveOptions options save=selected

Parents

  • Dear Ymmen,

    Ymmen said:
    In HB analysis when I sweep Pin1 from -40 to 0, I see Pin1 sweeping but Vin1 evaluates 3.16e-3 which corresponds to Pin1=-40. In other words, Vin1 does not change its value with the sweep. This problem is seen in maestro. ADEL didn't had this issue. In picture attached I have added netlist and maestro view. 

    It appears there is a known deficiency in IC6.1.8 shown at the following URL:

    support.cadence.com/.../techpubDocViewerPage

    and included below for your convenience. In your case, have you set Pin1 as a global variable?



    CCR 875662: A dependent expression always takes values from the global variable even if the local variable is enabled for a test

    Description: If a dependent expression is based on a variable that is overridden and enabled at the test level to use its local value, its output incorrectly uses the value specified for that variable at the global level.

    Solution: To use the local value in the dependent expression, define the expression inside another variable defined at the test level.

    Shawn

  • in reply to ShawnLogan

    Thanks for the reply Shawn. In my case, I am using ADE Explorer instead of ADE Assembler. So I think In my case all design variables are local and there is nothing defined as global variable. Pin1 is not defined explicitly as global variable.

    given info above, "Vin1" should have depended on "Pin1", as PIn1 is not defined as global variable?

    you can see the screenshot of maestro (ADE explorer) view in my first post.

    Thanks

  • in reply to Ymmen

    This is a bug. We've had some challenges in certain cases where dependent variables are prematurely evaluated, which breaks a variable being swept as in this case. The challenge is that you can have SKILL expressions in ADE which have to be evaluated before simulation, but some expressions could be handled by the simulator (such as these) and if you want to sweep one of the dependencies you really need it to be deferred.

    I'll file a CCR for this specific case (since I created a testcase to try it out). You can workaround it by using this instead:

    (2*50*10**((Pin1-30)/10))**0.5

    It seems to be the sqrt that is causing the trouble.

    Andrew

  • in reply to Andrew Beckett

    Thanks for the workaround Andrew. it would be great if you can post the CCR number once you file it. that way I can track it and apply the fix whenever available.

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