[SI-LIST] Re: W Model for transmission lines
- From: "Greim, Michael" <mgreim@xxxxxxxxxxxx>
- To: "Greim, Michael" <mgreim@xxxxxxxxxxxx>,"'richard2636@xxxxxxxxxx'" <richard2636@xxxxxxxxxx>,si-list@xxxxxxxxxxxxx
- Date: Mon, 24 Sep 2001 08:33:06 -0400
Here is the diff pair model. You may want to adjust
your copper/fr4 thickness and conductor shape based on
feedback from your fab vendor.
----------------Cut Here ---------------------------
********** W element tline definition**********
*
* The following defines a two conductor w
* element transmission line model for a dual
* stripline board structure with 0.5 oz trace
* thickness, 4 mil wide trace and 60 ohm target
* characteristic impedance. The six mil separation
* between the traces produces a diff impedance of
* 99.2 ohms. This was calculated using the Polar
* Instruments CITS25 Field Solver. This will model one
* coupled differential signal pair.
* Define the board material
.MATERIAL diel_fr4 DIELECTRIC ER=4.1
+LOSSTANGENT=0.020
.MATERIAL copper METAL CONDUCTIVITY=5.8e+07
* Define the cross section of the trace, rectangle
* 1/2 oz copper, 4 mil wide
.SHAPE rect RECTANGLE WIDTH=4mil, HEIGHT=0.7mil
* Define the dual stripline structure, two striplines
* between two 2 oz pwr/gnd planes. Each trace is 5 mils
* from the plane and five mils from the other trace.
.LAYERSTACK dual_sl_60,
+ LAYER= (copper,2.8mil), LAYER=(diel_fr4,16.4mil),
+ LAYER= (copper,2.8mil)
.FSOPTIONS opt1 PRINTDATA=YES
+ ComputeRo=yes ComputeRs=yes ComputeGo=Yes ComputeGd=yes
+ ACCURACY = HIGH
.MODEL cond2_diff W MODELTYPE=Fieldsolver,
+LAYERSTACK=dual_sl_60, FSOPTIONS=opt1,
+RLGCFILE=cond2diff.rlgc,
+CONDUCTOR= (MATERIAL=copper, SHAPE=rect, ORIGIN= (0, 7.8mil)),
+CONDUCTOR= (MATERIAL=copper, SHAPE=rect, ORIGIN= (10mil, 7.8mil))
****** End of the W element definition
******************************************************
* Example
* define a 4 inch instance of the w element stripline
* illustrated above.
*W1 lvdsout1a lvdsout1b 0 OUTA OUTB 0 FSmodel=cond2_diff
*+N=2 l=4000mil
------------------ Cut Here Too ----------------------------------
-----Original Message-----
From: Greim, Michael [mailto:mgreim@xxxxxxxxxxxx]
Sent: Monday, September 24, 2001 8:26 AM
To: 'richard2636@xxxxxxxxxx'; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: W Model for transmission lines
Hi Richard,
It is possible to create the W model from the
trace geometries and material properties. This
is outlined pretty well in the avanti hspice
manual within the Using Transmission Lines chapter
(chapter 19 I believe). You can recreate the
structure and use the internal field solver to
create what you need. I have included two pretty
well commented models that you can use as a refer
ence along with this chapter to get you moving.
One is a single ended line and one is a coupled
model. The later can be used as a diff pair or to
show the effects of coupling between two single
ended connectors.
Best of Luck and happy HSpicing. Feel free to
drop me a line if you have any other questions.
best regards,
Michael Greim
-----Original Message-----
From: richard hill [mailto:richard2636@xxxxxxxxxx]
Sent: Saturday, September 22, 2001 8:52 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] W Model for transmission lines
Hi,
I am new to the use of transmission line models
in HSPICE. I would like to create a W Model of
a transmission line. I am wondering how to derive
the RLGC parameters to incorporate it in my models.
I am struggling with this since it is not easy as the
U model where you just enter the trace geometry. If
I know the trace geometry is there an easy way to get
the parameters.
Thanks.
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