[SI-LIST] Re: modelling of wire as w-element transmission line
- From: Ted Mido <Tetsuhisa.Mido@xxxxxxxxxxxx>
- To: jxc9551@xxxxxxxxxxxxxxxxxx
- Date: Tue, 25 Jun 2002 12:22:23 -0700 (PDT)
Dear Jayanta,
I had a quick look at your field solver structure.
One thing which is not clear to me is, the model statement
of 'mymodel1.'
.MODEL mymodel1 W MODELTYPE=FieldSolver LAYERSTACK=mystack FSOPTIONS=myoption
+ RLGCFILE=test4.rlgc OUTPUTFORMAT=RLGCFILE CONDUCTOR=( SHAPE=myshape1,
+ ORIGIN=(1000, 3000), MATERIAL=mymetal), ( SHAPE=myshape2, ORIGIN=(1050,
3000), MATERIAL=mymetal)
If I look at the 'W1' statement this model statement
for 2 conductors should be
.MODEL mymodel1 W MODELTYPE=FieldSolver LAYERSTACK=mystack FSOPTIONS=myoption
+ RLGCFILE=test4.rlgc OUTPUTFORMAT=RLGCFILE
+ CONDUCTOR=( SHAPE=myshape1, ORIGIN=(1000, 3000), MATERIAL=mymetal)
+ CONDUCTOR=( SHAPE=myshape2, ORIGIN=(1050, 3000), MATERIAL=mymetal)
but still, these 2 conductors are overlapped together.
It seems that the metal conflict is causing a problem in
the solver.
In addition to this, here are some comments on it.
1. It would be better to use 'rectangle' instead of strip with
adding height of the conductor? Skin effect solver doesn't support
'strip' shape since we cannot define 2D mesh structure from it.
2. It would be better to begin the exam with smaller number
of mesh (N or NH/NW). I believe N=20-30 should be able to give
you relatively good result for this structure.
3. It would be better to use 2001.2 or later with specifying
copper reference plane in the layer stack? I believe this way takes
the return current distribution better.
best regards,
ted@synopsys
From: Jayanta Choudhury <jxc9551@xxxxxxxxxxxxxxxxxx>
Subject: [SI-LIST] modelling of wire as w-element transmission line
Date: Tue, 25 Jun 2002 11:56:10 -0500 (CDT)
> Hi,
> I want to model a wire or metal, used in the metal layers of semi
> conductor
> substrate preferably CMOS or GaAs high-speed circuits, in hspice 2000.4. The
> purpose to study signal corruption and distortion during the signal
> propagation
> thru the interconnects. I am using the W-element transmission line model for
> this and FSModel with SHAPE of metal as "strip". I want to see the waveforms
> in
> the situation described below.
> 1. Two transmission lines with multiple conductor passing accross each
> other.
> 2. Two transmission lines are at different heights
> 3. Both of them has same reference ground for near-end and far-end
> terminals,
> which is the bottom of the substrate.
> the top view is some what similar to what is shown below.
>
>
> | |
> --------------|-------|---------------------
> | |
> --------------|-------|---------------------
> | |
> | |
>
> If I model the longer lines with z-axix along their length, y-axis along
> their
> height and width along the x-axis I cannot model two conductors of the
> transmission line with shorter conductors. I can have only one conductor of
> that
> by having its width eqaul to the size of the actual length of the shorter
> conductor in strip SHAPE statement and length equal to actual width. But the
> spice file keeps running in an infinite loop.
>
> The spice file is attached.
>
> If any one has any clue to this please help me.
> Thank you.
> Jayanta Choudhury
>
>
> -- Attached file included as plaintext by Ecartis --
> -- File: across_lines.spice
> -- Desc: across_lines.spice
>
> *example. for observing two transmission lines lengths spreading accross each
> other
>
> .OPTION scale=0.1u
> .OPTION POST
>
> **a piece wise linear input waveform is used to model a step input
> v1 in1 GND pwl 5n 0v 5.06n sp, 14.94n sp, 15.0n 0v
> **V1 in1 gnd PULSE (0 5 2NS 0NS 0NS 50NS 100NS)
> **V1 in1 gnd SIN (0 5 1MEG)
>
> **W type transmission line state ment with driver side in1 and gnd and
> reciever side
> ** out1 and ground, Field Solver(FSmodel) model is defined below, number of
> conductors
> ** is N=2 length of the strip is l=25*scale(0.1um)
> W1 out00 out01 gnd in00 in01 gnd FSmodel=mymodel1 N=2 l=25000
> W2 out10 gnd in10 gnd FSmodel=mymodel2 N=1 l=500
>
> **Output Capacitance
> C1 out00 gnd 10fF
> c2 out01 gnd 10fF
> C3 out10 gnd 10fF
>
>
>
>
> .PARAM sp=3.3v
>
> **Model for solving equations and calculating RLGC values and writing them in
> RLGC
> **file specified by OUTPUTFORMAT, RLGCFILE is the file name ORIGIN is the
> co-ordinates
> **of strip MATERIAL is the metal for the conductor
> .MODEL mymodel1 W MODELTYPE=FieldSolver LAYERSTACK=mystack FSOPTIONS=myoption
> + RLGCFILE=test4.rlgc OUTPUTFORMAT=RLGCFILE CONDUCTOR=( SHAPE=myshape1,
> + ORIGIN=(1000, 3000), MATERIAL=mymetal), ( SHAPE=myshape2, ORIGIN=(1050,
> 3000), MATERIAL=mymetal)
>
> **Model for solving equations and calculating RLGC values and writing them in
> RLGC
> **file specified by OUTPUTFORMAT, RLGCFILE is the file name ORIGIN is the
> co-ordinates
> **of strip MATERIAL is the metal for the conductor
> .MODEL mymodel2 W MODELTYPE=FieldSolver LAYERSTACK=mystack FSOPTIONS=myoption
> + RLGCFILE=test5.rlgc OUTPUTFORMAT=RLGCFILE CONDUCTOR=( SHAPE=myshape2,
> + ORIGIN=(0, 5000), MATERIAL=mymetal)
>
>
> **mymetal has the characteristics of copper
> .MATERIAL mymetal METAL CONDUCTIVITY=57.6meg
>
> **dielectric has the characteristic of some example dielectric from manual
> .MATERIAL mydiel DIELECTRIC LOSSTANGENT=1.2e-3
>
> **Shape is Strip with width 1 micron and N=100 is number of discretization
> .SHAPE myshape1 STRIP WIDTH=500 N=100
>
> .SHAPE myshape2 STRIP WIDTH=25000 N=5000
>
> **LAYERSTACK is the stack of dielectric or metal layers associated with
> transmission
> **line, here it is a stack of default type metal named PEC and a dielectric
> ** specified by Material is background and thickness of PEC is 5um
> .LAYERSTACK mystack BACKGROUND=mydiel LAYER=(PEC, 5), LAYER=(mydiel, 5095)
>
> **Options for Field Solver model is defined GRIDFACTOR, which is multipled
> with
> **number of discretization specified in shape, PRINTDATA to print the datas
> **COMPUTEGD to calculate the conductance matrix Gd for rotation of dipoles
> under
> **the influence of alternating electric field, COMPUTERS computes skin effect
> **Resistance matrix Rs
> .FSOPTIONS myoption ACCURACY=HIGH GRIDFACTOR=1 PRINTDATA=YES COMPUTEGD=YES
> + COMPUTERS=YES
>
>
> .TRAN 0.01n 1000n
> .end
>
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