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Distributed Components are not suitable for QPSS analysis with Shooting engine

david73

I am simulating an amplifier with inductor bandwidth extension along with a sample hold, I would like to use QPSS to measure the total distortion.

I set the nport to use default interpolation, and see the following in the log.

I noticed that at first, the interpolation method chosed was bbspice, which is desirable, but then at IC, it switched to linear, and that seems to have caused the failure

I tried to explicitly set the interpolation method to bbspice, and i get the same failure.

Spectre (R) Circuit Simulator
Version 23.1.0.466.isr8 64bit -- 24 Apr 2024

~~~~~~~~~~~~~~~~~~~~~~
Pre-Simulation Summary
~~~~~~~~~~~~~~~~~~~~~~
- (Spectre X) Multi-threading. The recommended number of threads is [16, 32], consider adding +mt=16 or +mt=32 on command line. The estimated parallel scaling is from 12.0x to 15.0x. The estimated parallel scaling is completely based on circuit size and it is only an estimate. The actual simulation scaling can be heavily influenced by many other run-time factors, such as circuit activities, simulation features, machine loading, etc.
~~~~~~~~~~~~~~~~~~~~~~

Notice from spectre.
prebuff.route_to_th.XXind.nport_route: Automatically choose `interp` value to be `bbspice`.
prebuff.route_to_th.XXind.nport_route: Switch to `passivity=fit_enforce` for `interp=bbspice`.
S parameters are passive in file `/nfs/iil/disks/hip_ana_users_01/dgottesm/brkxmp_78/xmp_1278p3/soswa/.cadence/dfII/Sigrity/srdsadcfe/srdsadcfe_prebuff/layout/60C_tttt/p1278_6_emx_tttt/60C_tttt_p1278_6_emx_tttt.s6p'.


Perform S-parameter fitting for datafile: /nfs/iil/disks/hip_ana_users_01/dgottesm/brkxmp_78/xmp_1278p3/soswa/.cadence/dfII/Sigrity/srdsadcfe/srdsadcfe_prebuff/layout/60C_tttt/p1278_6_emx_tttt/60C_tttt_p1278_6_emx_tttt.s6p
Processing column 1 of 6 ...
Processing column 5 of 6 ...
Processing column 6 of 6 ...
Processing column 4 of 6 ...
Processing column 2 of 6 ...
Processing column 3 of 6 ...

Initial fitting finished, checking passivity violations...

prebuff.route_to_th.XXind.nport_route: No passivity violation detected.

Mean of relative fitting error is: 3.720318e-04.

S-parameter fitting finished successfully for datafile: /nfs/iil/disks/hip_ana_users_01/dgottesm/brkxmp_78/xmp_1278p3/soswa/.cadence/dfII/Sigrity/srdsadcfe/srdsadcfe_prebuff/layout/60C_tttt/p1278_6_emx_tttt/60C_tttt_p1278_6_emx_tttt.s6p.
Fitted s-parameters is stored in file: /p/hip/wa/dgottesm/brkxmp_78/xmp_1278p3//fitted_60C_tttt_p1278_6_emx_tttt.s6p

The maximum of mean relative fitting error is: 0.0015178495 at S4,5.

The maximum of mean absolute fitting error is: 0.00043399618 at S4,4.
Cache file of BBSpice ver. 2 is locked by 'dgottesm'.
Cache file of BBSpice ver. 2 is unlocked.

Total time required for BBSpice simulation: 2.32978 s.
Licensing Information:
[12:53:07.144010] Periodic Lic check successful

Fundamental signal_clk: period = 273.973 ps, freq = 3.65 GHz, harms = 3, oversample = 1.
Fundamental signal_input: period = 242.542 ps, freq = 4.123 GHz, harms = 3, oversample = 1.

*****************************************************************
Quasi-Periodic Steady State Analysis `qpss': largefund = 3.65 GHz
*****************************************************************

Notice from spectre during IC analysis, during periodic steady state analysis, during Quasi-Periodic Steady State Analysis `qpss'.
There are 12 IC nodes defined.

Finding DC approximate solution failed with try_fast_op=yes, continue running with try_fast_op=no.
Trying Fast DC 0 for initial conditions.
DC simulation time: CPU = 108.166 s, elapsed = 18.5401 s.
Important parameter values in pdisto iteration:
start = 56.0104 us
outputstart = 56.0104 us
stop = 56.0157 us
period = 273.973 ps
maxperiods = 20
steadyratio = 1
step = 5.27397 ps
maxstep = 1.36986 ps
ic = all
useprevic = no
skipdc = no
reltol = 10e-06
abstol(V) = 1 uV
abstol(I) = 1 pA
abstol(U) = 1 u
temp = 60 C
tnom = 27 C
tempeffects = all
errpreset = paranoid
method = gear2only
lteratio = 10
relref = sigglobal
cmin = 0 F
gmin = 1 pS
rabsshort = 1 mOhm


Error found by spectre during periodic steady state analysis, during Quasi-Periodic Steady State Analysis `qpss'.
ERROR (SPCRTRF-15161): Distributed Components are not suitable for QPSS analysis with Shooting engine. It's recommended to use Harmonic Balance engine for Distributed Components.
Warning from spectre during periodic steady state analysis, during Quasi-Periodic Steady State Analysis `qpss'.
WARNING (SPECTRE-555): Swap memory used = 116 kbytes. Swapping detected, resulting in slowed simulation. Consider running Spectre simulation on a machine with more available memory.

Analysis `qpss' was terminated prematurely due to an error.

Notice from spectre.
prebuff.route_to_th.XXind.nport_route: Automatically choose `interp` value to be `linear`.
S parameters are passive in file `/nfs/iil/disks/hip_ana_users_01/dgottesm/brkxmp_78/xmp_1278p3/soswa/.cadence/dfII/Sigrity/srdsadcfe/srdsadcfe_prebuff/layout/60C_tttt/p1278_6_emx_tttt/60C_tttt_p1278_6_emx_tttt.s6p'.

modelParameter: writing model parameter values to rawfile.

Parents
  • david73

    I tried to override the nport with ideal elements, i am getting the same error, here is a summary of the elements that are currently in my netlist, anything here considered a distributed element? (what is rtrk?)

    Circuit inventory:
    nodes 1025907
    delay 3
    isource 10
    rtrk 148
    umos5 131650
    vcvs 26
    vsource 122
    capacitor 1878875
    resistor 1007531

    Analysis and control statement inventory:
    info 6
    qpss 1

    ...

    Finding DC approximate solution failed with try_fast_op=yes, continue running with try_fast_op=no.
    Trying Fast DC 0 for initial conditions.
    DC simulation time: CPU = 91.6562 s, elapsed = 16.2197 s.
    Important parameter values in pdisto iteration:
    start = 56.0104 us
    outputstart = 56.0104 us
    stop = 56.0157 us
    period = 273.973 ps
    maxperiods = 20
    steadyratio = 1
    step = 5.27397 ps
    maxstep = 1.36986 ps
    ic = all
    useprevic = no
    skipdc = no
    reltol = 10e-06
    abstol(V) = 1 uV
    abstol(I) = 1 pA
    temp = 60 C
    tnom = 27 C
    tempeffects = all
    errpreset = paranoid
    method = gear2only
    lteratio = 10
    relref = sigglobal
    cmin = 0 F
    gmin = 1 pS
    rabsshort = 1 mOhm


    Error found by spectre during periodic steady state analysis, during Quasi-Periodic Steady State Analysis `qpss'.
    ERROR (SPCRTRF-15161): Distributed Components are not suitable for QPSS analysis with Shooting engine. It's recommended to use Harmonic Balance engine for Distributed Components.
    Warning from spectre during periodic steady state analysis, during Quasi-Periodic Steady State Analysis `qpss'.
    WARNING (SPECTRE-555): Swap memory used = 116 kbytes. Swapping detected, resulting in slowed simulation. Consider running Spectre simulation on a machine with more available memory.

    Analysis `qpss' was terminated prematurely due to an error.
    modelParameter: writing model parameter values to rawfile.

Reply
  • david73

    I tried to override the nport with ideal elements, i am getting the same error, here is a summary of the elements that are currently in my netlist, anything here considered a distributed element? (what is rtrk?)

    Circuit inventory:
    nodes 1025907
    delay 3
    isource 10
    rtrk 148
    umos5 131650
    vcvs 26
    vsource 122
    capacitor 1878875
    resistor 1007531

    Analysis and control statement inventory:
    info 6
    qpss 1

    ...

    Finding DC approximate solution failed with try_fast_op=yes, continue running with try_fast_op=no.
    Trying Fast DC 0 for initial conditions.
    DC simulation time: CPU = 91.6562 s, elapsed = 16.2197 s.
    Important parameter values in pdisto iteration:
    start = 56.0104 us
    outputstart = 56.0104 us
    stop = 56.0157 us
    period = 273.973 ps
    maxperiods = 20
    steadyratio = 1
    step = 5.27397 ps
    maxstep = 1.36986 ps
    ic = all
    useprevic = no
    skipdc = no
    reltol = 10e-06
    abstol(V) = 1 uV
    abstol(I) = 1 pA
    temp = 60 C
    tnom = 27 C
    tempeffects = all
    errpreset = paranoid
    method = gear2only
    lteratio = 10
    relref = sigglobal
    cmin = 0 F
    gmin = 1 pS
    rabsshort = 1 mOhm


    Error found by spectre during periodic steady state analysis, during Quasi-Periodic Steady State Analysis `qpss'.
    ERROR (SPCRTRF-15161): Distributed Components are not suitable for QPSS analysis with Shooting engine. It's recommended to use Harmonic Balance engine for Distributed Components.
    Warning from spectre during periodic steady state analysis, during Quasi-Periodic Steady State Analysis `qpss'.
    WARNING (SPECTRE-555): Swap memory used = 116 kbytes. Swapping detected, resulting in slowed simulation. Consider running Spectre simulation on a machine with more available memory.

    Analysis `qpss' was terminated prematurely due to an error.
    modelParameter: writing model parameter values to rawfile.

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