Re: [SI-LIST] : About the AC analysis with HSPICE

Ron Miller (rmiller@Brocade.COM)
Thu, 02 Sep 1999 08:53:26 -0700

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Rachild

Histocially, spice has no model for lossy transmission lines. Recently some people have
appriximated lossy transmission lines with R,C,Line models which they claim match
the lines they were trying to simulate. However, each model must depend on the
particular line. So, there will always be errors.

Frequency domain models, with frequency domain simulators can handle this
problem with the best fit bit but models never exactly match the real world.

Ron Miller

Rachild Chen wrote:

> All Sirs,
>
> Thanks for your advice.But I still have some questions.
>
> I use the .AC analysis to simulate the high frequency loss of
> transmission line.I use the .NET option of the .AC analysis.I mainly simulate the S21 parameter.
> But I found that the loss DB between simulation and test (I test with HP network analyer) is
> more and more different with frequency increasing.The loss DB of simulation is less than that of
> test.I want to know the reason.The .sp file is following:
> *******************************************************************
> .options probe post csdf
> .OPTION POST=1 ACOUT=1
> .OPTION BRIEF=0
> .OPTION SCALE=1u
> Vac nd_pin1 gnd ac 1v
> Rrerm cpin1 gnd 100k
> .NET V(cpin1) vac ROUT=50 RIN=50
> .AC DEC 100.00 30k 2000MEG
>
> Ws1 gnd nd_pin1 nd_pin2 gnd gnd gnd cpin1 cpin2 gnd gnd rlgcfile=hmbstrip42.rlgc n=4 l=14600mil
>
> .PRINT AC S11(DB) S21(DB)
>
> .END
> *************************************************************************
> The transmission line is from rlgcfile=hmbstrip42.rlgc which is extracted through :
>
> Vin1 nd_pin1 gnd pulse( 0v 3v 0.0n 0.3n 0.3n 2.15n 4.9n)
> Vin2 nd_pin2 gnd pulse(3v 0v 0.0n 0.3n 0.3n 2.15n 4.9n)
> *Vin1 nd_pin1 gnd pulse(0v 3.3v 0.0n 0.3n 0.3n 0.1n 4.8n)
> *Vin2 nd_pin1 gnd pulse(3.3v 0v 0.0n 0.3n 0.3n 0.1n 4.8n)
> *Vin3 nd_pin2 gnd pulse(0v 3.3v 0.0n 0.3n 0.3n 2.15n 4.9n)
> *Vin0 nd_pin4 gnd pulse(3v 0v 0.0n 0.3n 0.3n 2.15n 4.9n)
> .OPTION POST=2 ACOUT=1
> *.options brief = 0
> *.options probe post csd
> .options scale=1u
>
> Ws1 gnd nd_pin1 nd_pin2 gnd gnd gnd cpin1 cpin2 gnd gnd
> + Fsmodel=mother1 n=4 l=14600mil
> .material copper1 metal conductivity=5.96e+7 $inner
> .material copper2 metal conductivity=3.43e+7 $surface
> .material die_1 dielectric er=4.5 losstangent=1.7e-2 conductivity=1.55e-7
> .shape rect_1 rectangle width=10mil,height=1.38mil
> .layerstack stack_1 layer=(copper1, 1.38mil) layer=(die_1, 20mil ) layer=(die_1, 20.87mil ) layer=(copper1, 1.38mil)
> .Fsoptions wopt1 accuracy=high computegd=yes computers=yes computego=yes computero=yes printdata=yes gridfactor=3
>
> .model mother1 w modeltype=FieldSolver,layerstack=stack_1,fsoptions=wopt1,
> + rlgcfile='hmbstrip42.rlgc'
> + conductor= (material =copper1, shape=rect_1,origin=(0mil, 21.38mil))
> + conductor= (material =copper1, shape=rect_1,origin=(22mil,21.38mil))
> + conductor= (material =copper1, shape=rect_1,origin=(39mil, 21.38mil))
> + conductor= (material =copper1, shape=rect_1,origin=(61mil,21.38mil))
>
> .TRAN 100p 20n
> .end
> ********************************************************************************
> I want to know how should i assign values to 'ROUT' and 'RIN' in the .NET option
> of the .AC analysis of the HSPICE.I have seen that very different results can be got
> with different values of 'ROUT' and 'RIN'.What's the theory of .NET analysis to 'S21'
> in HSPICE?
> I also noticed that even i use different stimulus signals(100M,500M,1G or 2G) applying to transmission lines.There is no anything changed in the parameter matrix Ro,Lo,Co,Go,Rs,Gd.Why?How can i deal with these matrixes in exact
> frequency ?Perhaps it concerns somehow to the results of the loss of transmission line.
>
> Regards
>
> Rachild

--
Ronald B. Miller  _\\|//_  Signal Integrity Engineer
(408)487-8017    (' 0-0 ') fax(408)487-8017
     ==========0000-(_)0000===========
Brocade Communications Systems, 1901 Guadalupe Parkway, San Jose, CA  95131
rmiller@brocade.com,  rbmiller@sjm.infi.net

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<!doctype html public "-//w3c//dtd html 4.0 transitional//en"> Rachild

Histocially, spice has no model for lossy transmission lines.  Recently some people have
appriximated lossy transmission lines with R,C,Line models which they claim match
the lines they were trying to simulate.  However, each model must depend on the
particular line.  So, there will always be errors.

Frequency domain models, with frequency domain simulators can handle this
problem with the best fit bit but models never exactly match the real world.

Ron Miller

Rachild Chen wrote:

All Sirs,

Thanks for your advice.But I still have some questions.

I use the .AC analysis to simulate the high frequency loss of
transmission line.I use the .NET option of the .AC analysis.I mainly simulate the S21 parameter.
But I found that the loss DB between simulation and test (I test with HP network analyer) is
more and more different with frequency increasing.The loss DB of simulation is less than that of
test.I want to know the reason.The .sp file is following:
*******************************************************************
.options probe post csdf
.OPTION POST=1 ACOUT=1
.OPTION BRIEF=0
.OPTION SCALE=1u
Vac nd_pin1 gnd ac 1v
Rrerm cpin1 gnd 100k
.NET V(cpin1) vac ROUT=50 RIN=50
.AC DEC 100.00 30k 2000MEG

Ws1 gnd nd_pin1 nd_pin2 gnd  gnd  gnd cpin1 cpin2 gnd gnd rlgcfile=hmbstrip42.rlgc n=4 l=14600mil

.PRINT AC S11(DB) S21(DB)

.END
*************************************************************************
The transmission line is from rlgcfile=hmbstrip42.rlgc which is extracted through :

Vin1 nd_pin1 gnd pulse( 0v 3v 0.0n 0.3n 0.3n 2.15n 4.9n)
Vin2 nd_pin2  gnd pulse(3v 0v 0.0n 0.3n 0.3n 2.15n 4.9n)
*Vin1 nd_pin1 gnd pulse(0v 3.3v 0.0n 0.3n 0.3n 0.1n 4.8n)
*Vin2 nd_pin1 gnd pulse(3.3v 0v 0.0n 0.3n 0.3n 0.1n 4.8n)
*Vin3 nd_pin2 gnd pulse(0v 3.3v 0.0n 0.3n 0.3n 2.15n 4.9n)
*Vin0 nd_pin4 gnd pulse(3v 0v 0.0n 0.3n 0.3n 2.15n 4.9n)
.OPTION POST=2 ACOUT=1
*.options brief = 0
*.options probe post csd
.options scale=1u

Ws1 gnd nd_pin1 nd_pin2 gnd  gnd  gnd cpin1 cpin2 gnd gnd
+   Fsmodel=mother1 n=4 l=14600mil
.material       copper1      metal       conductivity=5.96e+7   $inner
.material       copper2      metal       conductivity=3.43e+7   $surface
.material    die_1       dielectric  er=4.5  losstangent=1.7e-2 conductivity=1.55e-7
.shape       rect_1      rectangle width=10mil,height=1.38mil
.layerstack     stack_1     layer=(copper1, 1.38mil) layer=(die_1, 20mil ) layer=(die_1, 20.87mil ) layer=(copper1, 1.38mil)
.Fsoptions  wopt1        accuracy=high  computegd=yes computers=yes computego=yes computero=yes printdata=yes  gridfactor=3

.model mother1  w modeltype=FieldSolver,layerstack=stack_1,fsoptions=wopt1,
+  rlgcfile='hmbstrip42.rlgc'
+      conductor= (material =copper1, shape=rect_1,origin=(0mil, 21.38mil))
+      conductor= (material =copper1, shape=rect_1,origin=(22mil,21.38mil))
+      conductor= (material =copper1, shape=rect_1,origin=(39mil, 21.38mil))
+      conductor= (material =copper1, shape=rect_1,origin=(61mil,21.38mil))

.TRAN 100p 20n
.end
********************************************************************************
   I want to know how should i assign values to 'ROUT' and 'RIN' in the .NET option
of the .AC analysis of the HSPICE.I have seen that very different results can be got
with different values of 'ROUT' and 'RIN'.What's the theory of .NET analysis to 'S21'
in HSPICE?
   I also noticed that even i use different stimulus signals(100M,500M,1G or 2G) applying to transmission lines.There is no anything changed in the parameter matrix Ro,Lo,Co,Go,Rs,Gd.Why?How can i deal with these matrixes in exact
frequency ?Perhaps it concerns somehow to the results of the loss of transmission line.

Regards

Rachild

-- 
Ronald B. Miller  _\\|//_  Signal Integrity Engineer
(408)487-8017    (' 0-0 ') fax(408)487-8017                 
     ==========0000-(_)0000=========== 
Brocade Communications Systems, 1901 Guadalupe Parkway, San Jose, CA  95131
rmiller@brocade.com,  rbmiller@sjm.infi.net
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