FPGA Central

I am starting to look at power integrity tools and would like to know what
is available and whether there are any "slimmed down" versions that can do
what I need at lower price than full-blown Sigrity-like packages.
Currently we use "spreadsheet" approach where we analytically compute plane
impedance based on self+mounting impedances of various types of caps plus
plane impedance. This is fairly accurate to 100MHz or so. However, it does
not help us at all in figuring out where the plane resonances are and where
we should place caps to help with them.

So, here is my wishlist. I don't require all to be addressed by same tool.
Depending on price - I'd be happy to get just some of the bullet points and
not all.

- Figure out plane impedance curve
- Figure out plane resonance - where should we place caps
- Figure out resistive losses plus current distribution
- Be able to figure out tradeoffs between using higher capacitance
plane/ground structure vs using large number of caps vs using different
types of caps.
- Do pre and post layout simulation
- Have non-SI expert be able to run the tools

So far Sigrity and HyperLynx PI (just announced) seem to do the job but at
quite substantial cost. I keep asking myself a question - what problem do
they solve vs cost (in license fees and training/simulation time) vs using
spreadsheet/simple simulation. So far I don't have a clear answer - thus I
am asking you for other ideas on approaching the power integrity problem.

Thank you
Aleks


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Aleks,

You raise valid and good questions, but I am afraid the answers may not
make you happy.

If you look around the tool market, there are several good commercial
tools on the market;
you named two of them, and we can add some more, for instance the
Ansoft/Ansys SiWave
and Cadence PI tools. These are the most sophisticated publicly
available tools at the moment,
and even these wont give you a design. Some tools have optimization
features built in, but
one could argue that the outcome of the optimization depends largely on
the initial constraints
you put in, so unless the user has some idea of what is going on, it
wont tell you what to do,
it just tells you the performance of the design you have come up with
(or within the constraints
you set in the optimizer).

It would be great to have both pre and post layout simulation
capabilities in the same package
at a low cost. When you look at the commercial tools, you will find
that they are all better
or more convenient only in one or the other. To get the cost down and
get you something
beyond lumped spreadsheet and rectangular-plane cavity-resonance
formulas, your best bet
is to look around among pre-layout tools. For instance, you might want
to try EZ PowerPlane
from http://www.ems-plus.com/ezpowerplane.html. When it comes to DC
drop, you can
do what-ifs with a pre-layout tool, but you really want and need a
post-layout check, because
pre-layout tools will not easily capture all the fine details (via
antipad dimensions, via barrel
resistance) that you eventually need for a reasonable answer.

We know that there are less demanding and more demanding designs in
terms of how much
work you may need to put into the power distribution network design to
get a satisfactory
product. If you deal with the category where you can stay competitive
only if you squeeze
out every drop of extra fat from your system, the possible alternatives
are: either you
outsource this aspect of the design (and beyond cost, this solution has
its own extra challenges),
or the company gradually gains the knowledge and expertise (and the
necessary tools) to
handle these tasks. So in this respect I view the last wish-list item
as not being compatible
with the rest of the list items. And finally, when you go through the
exercise of obtaining
the suitable tools and playing with them and a few designs have been
completed successfully,
you may find that you do not need the tools for certain tasks, because
you already gained
the knowledge so that you know what to do without simulations.

I hope this helps.

Regards,

Istvan Novak
SUN Microsystems


Aleksandr Oysgelt wrote:
> I am starting to look at power integrity tools and would like to know what
> is available and whether there are any "slimmed down" versions that can do
> what I need at lower price than full-blown Sigrity-like packages.
> Currently we use "spreadsheet" approach where we analytically compute plane
> impedance based on self+mounting impedances of various types of caps plus
> plane impedance. This is fairly accurate to 100MHz or so. However, it does
> not help us at all in figuring out where the plane resonances are and where
> we should place caps to help with them.
>
> So, here is my wishlist. I don't require all to be addressed by same tool.
> Depending on price - I'd be happy to get just some of the bullet points and
> not all.
>
> - Figure out plane impedance curve
> - Figure out plane resonance - where should we place caps
> - Figure out resistive losses plus current distribution
> - Be able to figure out tradeoffs between using higher capacitance
> plane/ground structure vs using large number of caps vs using different
> types of caps.
> - Do pre and post layout simulation
> - Have non-SI expert be able to run the tools
>
> So far Sigrity and HyperLynx PI (just announced) seem to do the job but at
> quite substantial cost. I keep asking myself a question - what problem do
> they solve vs cost (in license fees and training/simulation time) vs using
> spreadsheet/simple simulation. So far I don't have a clear answer - thus I
> am asking you for other ideas on approaching the power integrity problem.
>
> Thank you
> Aleks
>
>
>

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hi

some free tools available:
- FEMM. to do post-layout AC or DC voltage drop and current distribution
analysis on power planes (opensource, fully free, with windows version):
http://femm.foster-miller.net/wiki/HomePage
- Sphynx. frequency domain (s-parameter) analisys of power planes, with
capacitors. creating macromodel, checking resonant peaks.
you can download a demo with max 20000 nodes limitation and no CAD import,
or buy the full version.
http://www.powerintegrity.net/sphinx
- QUCS: circuit simulator with s-parameter file import for AC analysis. I
use this with models exported from sphynx, for a full power distribution
system freq.domain AC analysys (macromodelling). (opensource, fully free,
with windows version)
http://qucs.sourceforge.net/
example system anaysis:
http://www.buenos.extra.hu/download/...Design_prj.rar

To do a complete system analisys with siwave, you need to buy the Nexxim
circuit simulator too, also from Ansoft. dcdc converter, powerplane,
package, chip, package-caps... simulation together

"Have non-SI expert be able to run the tools" -i am not shure if this makes
any sense.

regards,
Istvan Nagy
Concurrent Technologies, UK.


----- Original Message -----
From: "Aleksandr Oysgelt" <aleks (AT) aristanetworks (DOT) com>
To: <si-list (AT) freelists (DOT) org>
Sent: Saturday, February 07, 2009 7:45 PM
Subject: [SI-LIST] Re: What are power integrity tools available out there?
Anything inexpensive that works?


>I am starting to look at power integrity tools and would like to know what
> is available and whether there are any "slimmed down" versions that can do
> what I need at lower price than full-blown Sigrity-like packages.
> Currently we use "spreadsheet" approach where we analytically compute
> plane
> impedance based on self+mounting impedances of various types of caps plus
> plane impedance. This is fairly accurate to 100MHz or so. However, it
> does
> not help us at all in figuring out where the plane resonances are and
> where
> we should place caps to help with them.
>
> So, here is my wishlist. I don't require all to be addressed by same
> tool.
> Depending on price - I'd be happy to get just some of the bullet points
> and
> not all.
>
> - Figure out plane impedance curve
> - Figure out plane resonance - where should we place caps
> - Figure out resistive losses plus current distribution
> - Be able to figure out tradeoffs between using higher capacitance
> plane/ground structure vs using large number of caps vs using different
> types of caps.
> - Do pre and post layout simulation
> - Have non-SI expert be able to run the tools
>
> So far Sigrity and HyperLynx PI (just announced) seem to do the job but at
> quite substantial cost. I keep asking myself a question - what problem do
> they solve vs cost (in license fees and training/simulation time) vs using
> spreadsheet/simple simulation. So far I don't have a clear answer - thus
> I
> am asking you for other ideas on approaching the power integrity problem.
>
> Thank you
> Aleks
>
>
> ------------------------------------------------------------------
> To unsubscribe from si-list:
> si-list-request (AT) freelists (DOT) org 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 (AT) freelists (DOT) org with 'help' in the Subject field
>
>
> List technical documents are available at:
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>
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> http://www.freelists.org/archives/si-list
> or at our remote archives:
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> Old (prior to June 6, 2001) list archives are viewable at:
> http://www.qsl.net/wb6tpu
>
>
>

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Old (prior to June 6, 2001) list archives are viewable at:
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How is it even possible to "design" a PDN when IC manufacturers do not
provide any information about the power characteristics of their parts such
and current draw vs. frequency. There are no models as to what is inside the
ICs at the power pins. So all the design tools in the world are not going to
solve that problem. It seems that IC manufacturers could provide this
information if they had the motivation to do so.

Joel


-----Original Message-----
From: si-list-bounce (AT) freelists (DOT) org [mailto:si-list-bounce (AT) freelists (DOT) org] On
Behalf Of Istvan Novak
Sent: Saturday, February 07, 2009 4:10 PM
To: Aleksandr Oysgelt
Cc: si-list (AT) freelists (DOT) org
Subject: [SI-LIST] Re: What are power integrity tools available out there?
Anything inexpensive that works?

Aleks,

You raise valid and good questions, but I am afraid the answers may not
make you happy.

If you look around the tool market, there are several good commercial
tools on the market;
you named two of them, and we can add some more, for instance the
Ansoft/Ansys SiWave
and Cadence PI tools. These are the most sophisticated publicly
available tools at the moment,
and even these wont give you a design. Some tools have optimization
features built in, but
one could argue that the outcome of the optimization depends largely on
the initial constraints
you put in, so unless the user has some idea of what is going on, it
wont tell you what to do,
it just tells you the performance of the design you have come up with
(or within the constraints
you set in the optimizer).

It would be great to have both pre and post layout simulation
capabilities in the same package
at a low cost. When you look at the commercial tools, you will find
that they are all better
or more convenient only in one or the other. To get the cost down and
get you something
beyond lumped spreadsheet and rectangular-plane cavity-resonance
formulas, your best bet
is to look around among pre-layout tools. For instance, you might want
to try EZ PowerPlane
from http://www.ems-plus.com/ezpowerplane.html. When it comes to DC
drop, you can
do what-ifs with a pre-layout tool, but you really want and need a
post-layout check, because
pre-layout tools will not easily capture all the fine details (via
antipad dimensions, via barrel
resistance) that you eventually need for a reasonable answer.

We know that there are less demanding and more demanding designs in
terms of how much
work you may need to put into the power distribution network design to
get a satisfactory
product. If you deal with the category where you can stay competitive
only if you squeeze
out every drop of extra fat from your system, the possible alternatives
are: either you
outsource this aspect of the design (and beyond cost, this solution has
its own extra challenges),
or the company gradually gains the knowledge and expertise (and the
necessary tools) to
handle these tasks. So in this respect I view the last wish-list item
as not being compatible
with the rest of the list items. And finally, when you go through the
exercise of obtaining
the suitable tools and playing with them and a few designs have been
completed successfully,
you may find that you do not need the tools for certain tasks, because
you already gained
the knowledge so that you know what to do without simulations.

I hope this helps.

Regards,

Istvan Novak
SUN Microsystems


Aleksandr Oysgelt wrote:
> I am starting to look at power integrity tools and would like to know what
> is available and whether there are any "slimmed down" versions that can do
> what I need at lower price than full-blown Sigrity-like packages.
> Currently we use "spreadsheet" approach where we analytically compute
plane
> impedance based on self+mounting impedances of various types of caps plus
> plane impedance. This is fairly accurate to 100MHz or so. However, it
does
> not help us at all in figuring out where the plane resonances are and
where
> we should place caps to help with them.
>
> So, here is my wishlist. I don't require all to be addressed by same
tool.
> Depending on price - I'd be happy to get just some of the bullet points
and
> not all.
>
> - Figure out plane impedance curve
> - Figure out plane resonance - where should we place caps
> - Figure out resistive losses plus current distribution
> - Be able to figure out tradeoffs between using higher capacitance
> plane/ground structure vs using large number of caps vs using different
> types of caps.
> - Do pre and post layout simulation
> - Have non-SI expert be able to run the tools
>
> So far Sigrity and HyperLynx PI (just announced) seem to do the job but at
> quite substantial cost. I keep asking myself a question - what problem do
> they solve vs cost (in license fees and training/simulation time) vs using
> spreadsheet/simple simulation. So far I don't have a clear answer - thus
I
> am asking you for other ideas on approaching the power integrity problem.
>
> Thank you
> Aleks
>
>
>

------------------------------------------------------------------
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Hello Joel,
What we have done is model this behavior through the knowledge of the design. For example, if we want to understand the effects of a PDN de-coupling strategy for a DDR3 IO bank, we could model the power supply bank and associated DDR3 data signals with an SIWAVE or PowerSI or your favorite. The model would include the section of the chip package (including any bond wire) and board. We typically can get the Spice model for the IO of the IC and through design knowledge can input the switching behavior of the DDR3 data. What is missing is the on-chip power/ground model. We have been able to get these models (at least the last couple of projects I have worked on) but I understand they may not be available to everyone.....depending. What should be available is the on-die decoupling model which coupled with the other models will get you real close to your PDN goals..
Regards,
-Jory



________________________________
From: Joel Brown <joel (AT) zmicro (DOT) com>
To: Istvan Novak <istvan.novak (AT) att (DOT) net>; Aleksandr Oysgelt <aleks (AT) aristanetworks (DOT) com>
Cc: si-list (AT) freelists (DOT) org
Sent: Monday, February 9, 2009 11:49:01 AM
Subject: [SI-LIST] Re: What are power integrity tools available out there? Anything inexpensive that works?

How is it even possible to "design" a PDN when IC manufacturers do not
provide any information about the power characteristics of their parts such
and current draw vs. frequency. There are no models as to what is inside the
ICs at the power pins. So all the design tools in the world are not going to
solve that problem. It seems that IC manufacturers could provide this
information if they had the motivation to do so.

Joel


-----Original Message-----
From: si-list-bounce (AT) freelists (DOT) org [mailto:si-list-bounce (AT) freelists (DOT) org] On
Behalf Of Istvan Novak
Sent: Saturday, February 07, 2009 4:10 PM
To: Aleksandr Oysgelt
Cc: si-list (AT) freelists (DOT) org
Subject: [SI-LIST] Re: What are power integrity tools available out there?
Anything inexpensive that works?

Aleks,

You raise valid and good questions, but I am afraid the answers may not
make you happy.

If you look around the tool market, there are several good commercial
tools on the market;
you named two of them, and we can add some more, for instance the
Ansoft/Ansys SiWave
and Cadence PI tools. These are the most sophisticated publicly
available tools at the moment,
and even these wont give you a design. Some tools have optimization
features built in, but
one could argue that the outcome of the optimization depends largely on
the initial constraints
you put in, so unless the user has some idea of what is going on, it
wont tell you what to do,
it just tells you the performance of the design you have come up with
(or within the constraints
you set in the optimizer).

It would be great to have both pre and post layout simulation
capabilities in the same package
at a low cost. When you look at the commercial tools, you will find
that they are all better
or more convenient only in one or the other. To get the cost down and
get you something
beyond lumped spreadsheet and rectangular-plane cavity-resonance
formulas, your best bet
is to look around among pre-layout tools. For instance, you might want
to try EZ PowerPlane
from http://www.ems-plus.com/ezpowerplane.html. When it comes to DC
drop, you can
do what-ifs with a pre-layout tool, but you really want and need a
post-layout check, because
pre-layout tools will not easily capture all the fine details (via
antipad dimensions, via barrel
resistance) that you eventually need for a reasonable answer.

We know that there are less demanding and more demanding designs in
terms of how much
work you may need to put into the power distribution network design to
get a satisfactory
product. If you deal with the category where you can stay competitive
only if you squeeze
out every drop of extra fat from your system, the possible alternatives
are: either you
outsource this aspect of the design (and beyond cost, this solution has
its own extra challenges),
or the company gradually gains the knowledge and expertise (and the
necessary tools) to
handle these tasks. So in this respect I view the last wish-list item
as not being compatible
with the rest of the list items. And finally, when you go through the
exercise of obtaining
the suitable tools and playing with them and a few designs have been
completed successfully,
you may find that you do not need the tools for certain tasks, because
you already gained
the knowledge so that you know what to do without simulations.

I hope this helps.

Regards,

Istvan Novak
SUN Microsystems


Aleksandr Oysgelt wrote:
> I am starting to look at power integrity tools and would like to know what
> is available and whether there are any "slimmed down" versions that can do
> what I need at lower price than full-blown Sigrity-like packages.
> Currently we use "spreadsheet" approach where we analytically compute
plane
> impedance based on self+mounting impedances of various types of caps plus
> plane impedance. This is fairly accurate to 100MHz or so. However, it
does
> not help us at all in figuring out where the plane resonances are and
where
> we should place caps to help with them.
>
> So, here is my wishlist. I don't require all to be addressed by same
tool.
> Depending on price - I'd be happy to get just some of the bullet points
and
> not all.
>
> - Figure out plane impedance curve
> - Figure out plane resonance - where should we place caps
> - Figure out resistive losses plus current distribution
> - Be able to figure out tradeoffs between using higher capacitance
> plane/ground structure vs using large number of caps vs using different
> types of caps.
> - Do pre and post layout simulation
> - Have non-SI expert be able to run the tools
>
> So far Sigrity and HyperLynx PI (just announced) seem to do the job but at
> quite substantial cost. I keep asking myself a question - what problem do
> they solve vs cost (in license fees and training/simulation time) vs using
> spreadsheet/simple simulation. So far I don't have a clear answer - thus
I
> am asking you for other ideas on approaching the power integrity problem.
>
> Thank you
> Aleks
>
>
>

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