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transient simulation accuracy

Ruixin

Hi, 

I am using an ideal delay cell in analoglib. With defined 1 ps delay, the cell is sometimes behaving abnormally with changed slopes. The smaller time strobe and max time step may solve this problem. 

Is this error an systematic offset in the simulation or it would change with the simulation state ? And is this cell similar to the real CMOS transistor, which means that in the transient simulation, the  transistors may appear same artifacts in the simulation ?  And what would be a correct time strobe set for 1 ps delay ? 

Thanks. 

Parents
  • Ruixin

     

    The schematic is as above. 

  • Andrew Beckett
    in reply to Ruixin

    It's not that clear to me what you're doing. Can you provide the netlist (input.scs) for the different configurations you are simulating? Since I can't see the simulation setup nor all the parameters from the schematic, the input.scs would be much easier.

    Andrew.

  • Ruixin
    in reply to Andrew Beckett

    Hi, Andrew, 

    V0 (net02 0) vsource type=pulse val0=1.5 val1=0 period=25e-9 rise=100e-12 \
    fall=100e-12 width=11.9e-9
    V10 (IN 0) vsource type=pulse val0=1.5 val1=0 period=25e-9 rise=100e-12 \
    fall=100e-12 width=11.9e-9
    DELAY198 (net07 OUT 0 IN) delay td=1e-12 gain=1
    simulatorOptions options reltol=1e-4 vabstol=1e-6 iabstol=1e-12 temp=27 \
    tnom=27 scalem=1.0 gmin=1e-12 rforce=1 \

    maxnotes=5 maxwarns=5 digits=5 cols=80 pivrel=1e-3 \
    sensfile="../psf/sens.output" checklimitdest=psf
    tran tran stop=200n errpreset=conservative write="spectre.ic" \
    writefinal="spectre.fc" annotate=status maxiters=5
    finalTimeOP info what=oppoint where=rawfile
    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
    saveOptions options save=allpub

    Thanks, 

    Ruixin

Reply
  • Ruixin
    in reply to Andrew Beckett

    Hi, Andrew, 

    V0 (net02 0) vsource type=pulse val0=1.5 val1=0 period=25e-9 rise=100e-12 \
    fall=100e-12 width=11.9e-9
    V10 (IN 0) vsource type=pulse val0=1.5 val1=0 period=25e-9 rise=100e-12 \
    fall=100e-12 width=11.9e-9
    DELAY198 (net07 OUT 0 IN) delay td=1e-12 gain=1
    simulatorOptions options reltol=1e-4 vabstol=1e-6 iabstol=1e-12 temp=27 \
    tnom=27 scalem=1.0 gmin=1e-12 rforce=1 \

    maxnotes=5 maxwarns=5 digits=5 cols=80 pivrel=1e-3 \
    sensfile="../psf/sens.output" checklimitdest=psf
    tran tran stop=200n errpreset=conservative write="spectre.ic" \
    writefinal="spectre.fc" annotate=status maxiters=5
    finalTimeOP info what=oppoint where=rawfile
    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
    saveOptions options save=allpub

    Thanks, 

    Ruixin

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