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Siming Pan | 2 Apr 2011 00:14
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Re: ferrites article on PCD&F and other stories

Hi all,
   I have a question here: why could board resonance be the price of using
ferrite beads? I agree that small isolated board would cause severe board
resonances. However, the first modal resonance is always at several MHz. For
board-level PDN design, we usually only care about the inductive curve up to
100 MHz. Chip with proper on-die decap and package will never see those
board resonances.
   I think one advantage of using shared power plane for multiple chips is
that all decaps on this power plane can be shared to low the impedance.
However, the total loop inductance is consisted by two portions. One is the
inductance caused by power vias connecting with decaps and the other portion
is inductance due to IC power pin. Although by combing the power planes the
inductance of decap via can be reduced, the mutual effects caused by mutual
inductance of the IC power pins may worse the situations, even when the IC
noise current of multiple chips is at the similar level. So I always use
ferrite beads to isolate chips and control the PDN impedance for each chip.
Although to use ferrite beads might not be the best solution to optimize
decaps, it is always safe to prevent interferences.
Regards,
Siming Pan
Cisco Systems

On Fri, Apr 1, 2011 at 1:54 PM, Eric Bogatin <eric@...> wrote:

> Hi folks-
>
>
> I thought you might be interested in the piece I wrote for PCD&F magazine
> based on Steve Weir's DesignCon talk on ferrites. Check it out here:
>
(Continue reading)

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Istvan Novak | 2 Apr 2011 02:46
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Re: ferrites article on PCD&F and other stories

Hi Siming,

Nothing is free.  When we have a series element in the power 
distribution network, it will
change the noise characteristics.  The usual goal is to have the series 
element so that
the attenuation through the filter reduces the noise.  The price depends 
on how we do
the design.  If the filter is not properly done, it will attenuate the 
noise in one frequency
range, but may increase the noise at other frequencies.  Assuming the 
design is done
properly, the next potential problem is resonance in the impedance 
profile, which was
the essence of your question.

The resonance may cause several issues: if the resonance frequency is 
below the cutoff frequency
of the board-package interface, the resulting noise can get to the 
silicon and can cause
problems there. If that is not the case, but sensitive signal vias go 
through vertically
the resonating plane cavities, those signals may suffer dips in their 
transmission profiles
at the resonance frequencies.  Though the resonances created by ferrite 
beads and inductors
are usually low enough in frequency that this is an unlikely, but still 
possible issue.

In the impedance profile,. the primary resonance created by the ferrite
(Continue reading)

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steve weir | 2 Apr 2011 03:20

Re: ferrites article on PCD&F and other stories

Siming, you can read the paper available on the ipblox website:  
www.ipblox.com/papers.html.  It directly addresses your issues.

A ferrite bead unless properly compenstated introduces simple L-C 
resonances.  Breaking the board up into smaller sections shifts the 
modal frequencies, and increases their Q.

Combining caps and loads does not reduce the worst-case noise.  It 
improves the average case, provided that by combining resonance issues 
were not created that did not exist before.  The resonance issue cuts 
both ways which means care must be taken to make sure comparisons are 
apples to apples.

Steve.

On 4/1/2011 3:14 PM, Siming Pan wrote:
> Hi all,
>     I have a question here: why could board resonance be the price of using
> ferrite beads? I agree that small isolated board would cause severe board
> resonances. However, the first modal resonance is always at several MHz. For
> board-level PDN design, we usually only care about the inductive curve up to
> 100 MHz. Chip with proper on-die decap and package will never see those
> board resonances.
>     I think one advantage of using shared power plane for multiple chips is
> that all decaps on this power plane can be shared to low the impedance.
> However, the total loop inductance is consisted by two portions. One is the
> inductance caused by power vias connecting with decaps and the other portion
> is inductance due to IC power pin. Although by combing the power planes the
> inductance of decap via can be reduced, the mutual effects caused by mutual
> inductance of the IC power pins may worse the situations, even when the IC
(Continue reading)

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Jimmy Lee | 2 Apr 2011 19:04
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one question for HSPIC and IBIS_AMI

Hi SI expert
Something confused me several days

I need to perform serdes channel simulations with mixed models(HSPICE and IBIS-AMI). Is it possible? EDA
tools I have are HSPICE 2010.03-sp1, SIGXP 16.2, Hyperlynx 8.0. I found neither sigxp nor hyperlynx on
there version support IBIS-AMI. HSPICE is said to support IBIS-AMI in Statistical Eye Analysis mode with
.stateye command. Is there a tutorial about how to do a serdes channel simulation with mixed hspice and
ibis-ami models in HSPICE? BTW, could I just do a transient simulation with the preemphasis or
equaliztion options compiled in .ami or .dll file?

Thanks
Jimmy

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steve weir | 2 Apr 2011 19:25

Re: one question for HSPIC and IBIS_AMI

Extract s-parameters for the channel and use those with HSPICE.

Steve.
On 4/2/2011 10:04 AM, Jimmy Lee wrote:
> Hi SI expert
> Something confused me several days
>
> I need to perform serdes channel simulations with mixed models(HSPICE and IBIS-AMI). Is it possible? EDA
tools I have are HSPICE 2010.03-sp1, SIGXP 16.2, Hyperlynx 8.0. I found neither sigxp nor hyperlynx on
there version support IBIS-AMI. HSPICE is said to support IBIS-AMI in Statistical Eye Analysis mode with
.stateye command. Is there a tutorial about how to do a serdes channel simulation with mixed hspice and
ibis-ami models in HSPICE? BTW, could I just do a transient simulation with the preemphasis or
equaliztion options compiled in .ami or .dll file?
>
>
> Thanks
> Jimmy
>
>
> ------------------------------------------------------------------
> To unsubscribe from si-list:
> si-list-request@... with 'unsubscribe' in the Subject field
>
> or to administer your membership from a web page, go to:
> http://www.freelists.org/webpage/si-list
>
> For help:
> si-list-request@... with 'help' in the Subject field
>
>
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Kaufer, Steve | 2 Apr 2011 20:46
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Re: one question for HSPIC and IBIS_AMI

Hi Jimmy,

You're using an older version of HyperLynx; the current version has IBIS-AMI support. If you need more
information, please contact me off-line.

Regards,

Steve Kaufer

-----Original Message-----
From: si-list-bounce@...
[mailto:si-list-bounce@...] On Behalf Of Jimmy Lee
Sent: Saturday, April 02, 2011 10:05 AM
To: si-list@...
Subject: [SI-LIST] one question for HSPIC and IBIS_AMI

Hi SI expert
Something confused me several days

I need to perform serdes channel simulations with mixed models(HSPICE and IBIS-AMI). Is it possible? EDA
tools I have are HSPICE 2010.03-sp1, SIGXP 16.2, Hyperlynx 8.0. I found neither sigxp nor hyperlynx on
there version support IBIS-AMI. HSPICE is said to support IBIS-AMI in Statistical Eye Analysis mode with
.stateye command. Is there a tutorial about how to do a serdes channel simulation with mixed hspice and
ibis-ami models in HSPICE? BTW, could I just do a transient simulation with the preemphasis or
equaliztion options compiled in .ami or .dll file?

Thanks
Jimmy

------------------------------------------------------------------
(Continue reading)

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Jimmy Lee | 2 Apr 2011 20:48
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Re: one question for HSPIC and IBIS_AMI

Hi Steve,

Thank you for your prompt reply.

I  have already had channel S-parameters. But I have no experience to do a simulation in HSPICE Statistical
Eye Analysis mode. Is there any  tutorial about it? Or the right way to me is just to read help of Hspice? 

________________________________________
addresser: steve weir [weirsi@...]
send time: 2011-4-3 1:25
addressee: Jimmy Lee
Cc: si-list@...
Title: Re: [SI-LIST] one question for HSPIC and IBIS_AMI

Extract s-parameters for the channel and use those with HSPICE.

Steve.
On 4/2/2011 10:04 AM, Jimmy Lee wrote:
> Hi SI expert
> Something confused me several days
>
> I need to perform serdes channel simulations with mixed models(HSPICE and IBIS-AMI). Is it possible? EDA
tools I have are HSPICE 2010.03-sp1, SIGXP 16.2, Hyperlynx 8.0. I found neither sigxp nor hyperlynx on
there version support IBIS-AMI. HSPICE is said to support IBIS-AMI in Statistical Eye Analysis mode with
.stateye command. Is there a tutorial about how to do a serdes channel simulation with mixed hspice and
ibis-ami models in HSPICE? BTW, could I just do a transient simulation with the preemphasis or
equaliztion options compiled in .ami or .dll file?
>
>
> Thanks
(Continue reading)

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steve weir | 2 Apr 2011 21:19

Re: one question for HSPIC and IBIS_AMI

Jimmy you can look on solve-net for a tutorial.  I do not know of one 
off hand.

Steve.
On 4/2/2011 11:48 AM, Jimmy Lee wrote:
> Hi Steve,
>
> Thank you for your prompt reply.
>
> I  have already had channel S-parameters. But I have no experience to do a simulation in HSPICE Statistical
Eye Analysis mode. Is there any  tutorial about it? Or the right way to me is just to read help of Hspice?
>
> ________________________________________
> addresser: steve weir [weirsi@...]
> send time: 2011-4-3 1:25
> addressee: Jimmy Lee
> Cc: si-list@...
> Title: Re: [SI-LIST] one question for HSPIC and IBIS_AMI
>
> Extract s-parameters for the channel and use those with HSPICE.
>
> Steve.
> On 4/2/2011 10:04 AM, Jimmy Lee wrote:
>> Hi SI expert
>> Something confused me several days
>>
>> I need to perform serdes channel simulations with mixed models(HSPICE and IBIS-AMI). Is it possible?
EDA tools I have are HSPICE 2010.03-sp1, SIGXP 16.2, Hyperlynx 8.0. I found neither sigxp nor hyperlynx on
there version support IBIS-AMI. HSPICE is said to support IBIS-AMI in Statistical Eye Analysis mode with
.stateye command. Is there a tutorial about how to do a serdes channel simulation with mixed hspice and
(Continue reading)

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Eric Bogatin | 1 Apr 2011 22:54
Favicon

ferrites article on PCD&F and other stories

Hi folks-

I thought you might be interested in the piece I wrote for PCD&F magazine
based on Steve Weir's DesignCon talk on ferrites. Check it out here:

http://pcdandf.com/cms/component/content/article/171-current-issue/7893-sign
al-integrity-insights. 

You can add comments to the article on the PCD&F site, if you are so
inclined. 

I've also been writing a blog for EE Times on SI topics, based on interviews
with experts.  

http://www.eetimes.com/electronics-blogs/4207357/BeTheSignal/

If you have a suggestion for a topic or someone for me to interview, drop me
a note- offline, please!

Additional info on other SI topics is on my web site, www.beTheSignal.com
<http://www.bethesignal.com/> .

--eric

*******************************************************
Dr. Eric Bogatin, Signal Integrity Evangelist
Bogatin Enterprises
Setting the Standard for Signal Integrity Training
No Myths Allowed Webinar Series
Public Classes
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Muranyi, Arpad | 3 Apr 2011 19:03
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Re: one question for HSPIC and IBIS_AMI

Jimmy,

First, like Steve Kaufer already stated, you need to get
the latest version of HyperLynx which does have IBIS-AMI
support.

Second, IBIS-AMI simulations can't be done in "mixed mode".
You have to have AMI models for both Tx and Rx to be able
to use algorithmic (AMI) models.  You can't have a SPICE
or regular IBIS model on one end and an algorithmic model
on the other end.  These two types of models do not mix
(like water and oil).

The reason is because regular SPICE and IBIS models are
simulated by an iterative circuit solver simulator which
solves the voltages and currents in the circuit using
Ohm's law, Kirchhoff's law etc... for each node voltage
and branch current.  AMI models, on the other hand start
with an impulse response of the channel and process that
with signal processing algorithms.  This technique
only processes the waveform seen at the receiver
(usually).

I hope this gives you a better understanding of the nature
of these two types of models and simulations.

Arpad
=============================================================

-----Original Message-----
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Gmane