[SI-LIST] Re: Via model
- From: "Carrier, Patrick" <Patrick_Carrier@xxxxxxxxxx>
- To: "Zaiyi Liao" <zaiyi.liao@xxxxxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Fri, 20 Nov 2009 12:14:56 -0700
Hello Zaiyi--
The via models used for SI simulation in HyperLynx are certainly more
accurate than just a simple "cap" model. They are based on
decompositional analytical solutions and have been proven accurate out
to multi-GHz frequency ranges. I suggest contacting your local AE or
support engineer for more detail on the proper via model to use for your
application. I have contacted our Support team and they will be
contacting you shortly as well.
Without seeing the S-parameter in question I can't comment on the
"fluctuations" you are seeing but realize that all finite structures
will have some resonances associated with them.
Depending on your target application, you may also need to worry about
the bypassing of the via, and may need a via model which includes a
complete modeling of your bypass caps, stitching vias, and planes, which
can also be generated by HyperLynx (your AE will have more information
on this).
--Pat
Patrick Carrier
Technical Marketing Engineer
High Speed Design
Mentor Graphics Corporation
Patrick_Carrier@xxxxxxxxxx
ph. (512) 425-3015
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of Zaiyi Liao
Sent: Friday, November 20, 2009 3:00 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Via model
Hello all:
Can you give me some knowledge of via model?
Now I'm using Hyperlynx. Via model in hyperlynx is a short
transmission line with two caps to GND on each side . The influnece of
stub is exhibited in value of caps, the longer the stub is , the lager
the caps
will be. I simulate the S21 of such via model(Spice description below)
,I find there will be a fluctuation in S21(-2dB in ~7GHz, -0.2dB at
14Ghz). I think it's unreasonable, what is your opinion? What's the
wrong of this
model?
I'd like you can talk something about how to establish via model
and how to check if this model is reasonable. Thank you very mush!
BR//Zaiyi Liao
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~~~~~~~~~~~~
.SUBCKT thru10_22_B00
* Right Via
* Padstack: "thru10_22_B00" Drill.0mils
* layers to connect (ports)
*** connection to layer "SIGNAL_1_B00"
+ L1_1
*** connection to layer "SIGNAL_14_B00"
+ L27_1
C000 L1_1 0 2.80981e-014
T052 L1_1 0 L27_1 0 Z0'.3369 TD=3.26191e-011
C052 L27_1 0 1.65302e-013
* Left Via
* Padstack: "thru10_22_B00" Drill.0mils
* layers to connect (ports)
*** connection to layer "SIGNAL_1_B00"
+ L1_2
*** connection to layer "SIGNAL_14_B00"
+ L27_2
C000 L1_2 0 2.80981e-014
T052 L1_2 0 L27_2 0 Z0'.3369 TD=3.26191e-011
C052 L27_2 0 1.65302e-013
.ENDS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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