[SI-LIST] Re: time domain simulation w/ PDN planes
- From: "Istvan Nagy" <buenos@xxxxxxxxxxx>
- To: <sherman.chen@xxxxxxx>, <nilesh_kamdar2@xxxxxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Wed, 22 Oct 2014 18:51:07 -0700
Hi,
What you need in your 3D model:
- port for Dp pin at TX chip
- port for Dm pin at TX chip
- port for VCC pin at TX chip
- port for GND pin at TX chip
- port for Dp pin at RX chip
- port for Dm pin at RX chip
- port for VCC pin at RX chip (maybe leave it out)
- port for GND pin at RX chip (maybe leave it out)
- port for VCC pin at VRM
- port for GND pin at VRM
- full size power plane, not only around the trace, to include plane
resonances too. no cookie cutters.
- all decoupling caps from that vcc plane to gnd plane (they dampen the
plane waves)
- all antipads on the power and gnd plane to include plane waves passing or
resonating through antipad fields, especially under the BGAs to the next row
creating crosstalk.
-You may also want to simulate "plane-wave-assited crosstalk" so include 1-2
aggressor nets on each side and all their ports.
-the via models need to be accurate, as Yuriy mentioned, as these are the
primary interaction points between signal and plane. (as well as the buffers
creating SSN).
I don't think you need any ports half-way, but the simulator will calculate
voltages/waves in every cell anyway.
Then in a channel sim (like ADS) hook the many-port sparam model up with vrm
model and ibis models (that have a power pin).
All these structures together create a huge model, like 100k++ cells. I
tried to simulate (few years ago) something like this with Agilent Momentum
in MW mode with an 8core dual processor server, and it took several days.
Regards,
Istvan Nagy
-----Original Message-----
From: 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_Touchstonev2SIPISParameterModels.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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