[SI-LIST] Re: time domain simulation w/ PDN planes
- From: "Yuriy Shlepnev" <shlepnev@xxxxxxxxxxxxx>
- To: <sherman.chen@xxxxxxx>, <nilesh_kamdar2@xxxxxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Wed, 22 Oct 2014 13:12:13 -0700
Hi Sherman,
Now you explained the problem :-)
All hybrid solvers (both frequency or time domain) that use separate
transmission line and transmission plane (parallel plane) models will not
take this type of coupling into account.
The reason is simple. Transmission plane model of the parallel planes
includes electric field with only one component perpendicular to the planes
and magnetic field components parallel to the planes (may be formalized as
TM waves). These fields couple or excited by only to the currents flowing in
the direction orthogonal to the planes - currents on vias for instance. On
the other hand, T-line strips have currents predominantly parallel to the
planes and are simulated in these hybrid solvers separately with the
coupling only at the vertical transitions.
In a simplified case with parallel planes with strips between them and TM
waves propagating along the strips will be exactly orthogonal (do not
interact) to the TEM waves propagating along the strips (even in presence of
dielectric and conductor losses). Such modes do not interact!
In reality, TM waves are not exactly TM and do not propagate along the
strips. Small coupling takes place mostly due to discontinuities,
inhomogeneities and losses. To construct a model with the coupling, you will
need 3D analysis that accounts for all major factors contributing to the
coupling. You should see that the coupling at the transition to the strip
will be dominant. Though, I have not seen such investigation - may be
someone on this list can provide further references.
Best regards,
Yuriy
Yuriy Shlepnev, Ph.D.
President, Simberian Inc.
3030 S Torrey Pines Dr. Las Vegas, NV 89146, USA
Office +1-702-876-2882; Fax +1-702-482-7903
Cell +1-206-409-2368; Virtual +1-408-627-7706
Skype: shlepnev
www.simberian.com
Simbeor - Accurate, Fast, Easy and Affordable Electromagnetic Signal
Integrity Software
2010 and 2011 DesignVision Award Winner
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Chen, Sherman
Sent: Wednesday, October 22, 2014 11:47 AM
To: nilesh_kamdar2@xxxxxxxxxxxx; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: time domain simulation w/ PDN planes
Nilesh,
Thanks for the paper. My question is regarding how to model the coupling
from PDN to the transmission line, not the transmitter or the receiver chip.
The coupling effect across the whole span of the tline need to be
calculated. To do that in circuit simulator what I can think of is to use a
multi-port sparam which's ports are extracted btw the locations along the
tline and the VRM, at the interval of say lambda/20. At each location the
port need to be set at four points: DP+, DP-, Vcc on power plane, and GND on
the ground plane.
Any comments on this thought?
-----Original Message-----
From: nilesh_kamdar2@xxxxxxxxxxxx [mailto:nilesh_kamdar2@xxxxxxxxxxxx]
Sent: Wednesday, October 22, 2014 11:38 PM
To: si-list@xxxxxxxxxxxxx; Chen, Sherman
Subject: RE: [SI-LIST] time domain simulation w/ PDN planes
Sherman
If I understood your question correctly, I believe that this simulation can
be handled in ADS. To do this you need to create an SI/PI model of the
physical interconnects that includes all the power/ground planes and also
signal lines. Then you can apply specific time domain stimulus in a
Transient simulation.
Here is a DesignCon 2014 paper that explains how we can do this:
Paper:
http://cp.literature.agilent.com/litweb/pdf/5991-4083EN.pdf
Slides:
http://www.xilinx.com/events/designcon2014/11_WE5Slides_Touchstonev2SIPISPar
ameterModels.pdf
If you have more questions about this technique, you can contact me offline.
Thanks
Nilesh Kamdar
Applications Engineer, Keysight Technologies
-----Original Message-----
----------------------------------------------------------------------
Msg: #1 in digest
From: "Chen, Sherman" <sherman.chen@xxxxxxx>
Subject: [SI-LIST] time domain simulation w/ PDN planes
Date: Tue, 21 Oct 2014 14:07:19 +0000
Hello experts,
I'm trying to evaluate the impact of power plane noise on the HS signals.
The sim setup would require to apply a noise source on the PDN (somewhere
btw power plane and ground plane), also a PRBS source at the initial end of
the t-line. To my knowledge it looks only Cadence Sigrity Speed2000 can run
such SI/PI combined sim since the feedback I got from Keysight and ANSYS
both said that neither ADS nor SIWave can handle such sim case where time
domain sim needs to be run w/ the noise coupled from power/ground plane.
Note the coupling needs to be from the whole plane rather than injected at
one point for the latter we can simply use a sparam model of the PDN as the
means of noise injection but this would not be the equivalent of the plane
coupling, right?
Any suggestion will be appreciated.
Best Regards,
Sherman Chen
Signal Integrity
EMC Global Hardware Engineering
Tel: +86 21 60951100-3329
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