[SI-LIST] Re: plane RLGC Debye model
- From: "Yuriy Shlepnev" <shlepnev@xxxxxxxxxxxxx>
- To: "'Istvan Nagy'" <buenos@xxxxxxxxxxx>, "'steve weir'" <weirsi@xxxxxxxxxx>
- Date: Sat, 15 Nov 2008 11:48:42 -0800
Istvan,
If you have dielectric constant value at 1 MHz, dielectric constant at 20
GHz may be about 10% smaller for a composite PCB material (as observed in
multiple experiments). It may be not important for practical PDN design as
Steve mentioned and simple 1-frequency approximation for G and C may work
just fine. The same is valid for R and L. Though, in case of very closely
spaces planes (with less than 5 mils distance), the effect of internal
inductance of the metal planes in combination with the dielectric dispersion
can cause significant shifts of resonances even at lower frequencies
important for PDN design.
If you want to build the lattice-type equivalent circuit model valid over
3-4 decades in frequency and accounting for frequency variations of
dielectric constant and internal plane inductance, it can be done with the
broadband transmission plane model (see my paper "Transmission plane models
for parallel-plane power distribution system and signal integrity analysis"
in proceedings of 22-nd ACES symposium, 2006, p. 382-389, also available at
http://www.shlepnev.com/Publications/ACES2006c.pdf). The model is validated
with experiments in I. Novak, J. Miller Frequency-domain characterization of
power distribution networks - Artech House, 2007, chapter 7 and in J.
Miller, G. Blando, B. Williams, I. Novak "Impact of PCB Laminate Parameters
on Suppressing Modal Resonances" - DesignCon2008.
Here are possible steps to build broad-band SPICE model for PDN:
1) Use equation (3) from the cited ACES paper for frequency-dependent
admittance per square Ys and fit it with 3-4 real poles evenly distributed
over you frequency band to get rational approximation form (9)
2) Use equation (11) for sheet impedance of the plane pair Zs and fit it
with 3-4 real poles to get the rational approximation form (12)
3) Define cell size dx and dy for your equivalent lattice model
4) Compute admittance of one sell as Ys*dx*dy - the rational approximation
from step 1 immediately gives you the second Foster form of GC or RC network
for the cell node
5) Compute impedance of one sell as Zs*dx/dy for x-axis and as Zs*dy/dx for
y-axis - the rational approximation from step 2 immediately gives you the
second Foster form of RL network for the x and y branches of your cell
6) Combine cells into a 2D equivalent circuit of the plane pair
Note that the final 2D model is similar to a lumped broad-band model for a
transmission line.
Best regards,
Yuriy Shlepnev
www.simberian.com
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Istvan Nagy
Sent: Saturday, November 15, 2008 4:45 AM
To: steve weir
Cc: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: plane RLGC Debye model
hi
the only thing what i have is the dielectric thickness, and Er@1MHz, as
usual. i normally dont haave measurement data.
the simple RLGC models dont take the frequency-dependeny of the Er into
account, skin effect,...
these can be described by simple equations, but how to kame a lumped model
based on equations containing E^x... and similar things.
at least these 2 effects should be included.
Er(f)=Er(f0)*(jf/f0)^(-0.006366) this gives a frequency dependency for C
and G
R is dependent on f because of the skin effect.
somehow L is also dependent on frequency?
because it is for a unit-cell model, it shouldnt need more then very few
parameters, like dielectric thickness, Er(f0), f, cell size.
Istvan
----- Original Message -----
From: "steve weir" <weirsi@xxxxxxxxxx>
To: "Istvan Nagy" <buenos@xxxxxxxxxxx>
Cc: <si-list@xxxxxxxxxxxxx>
Sent: Saturday, November 15, 2008 12:29 PM
Subject: [SI-LIST] Re: plane RLGC Debye model
> Istvan what data do you have? Do you have measurements from material
> samples?
>
> For most power work, it is sufficient to use a single value for tangent
> loss. If you get the other parameters correct, then the models will
> tend to show slightly higher peak impedances at the modal resonances
> than measurements out above 1GHz, but the difference is typically not
> great.
>
> Steve.
> Istvan Nagy wrote:
>> hi
>> how can i calculate the Ri, Li, Gi, Ci parameters for a frequency
>> dependent unit-cell Debye RLGC model for a power/gnd plane pair? 1st
>> order or up to 3rd order Debye model would be good.
>> are there any equations?
>> (Debye models introduce additional RL and GC elements into the 4 element
>> original RLGC model to reflect the frequency-dependency, and with staying
>> with basic circuit elements, suitable for spice)
>>
>> i would like to make frequency dependednt spice 3f5 models (not w-element
>> model, since its not compatible with most of the spices) from arbitrary
>> power planes, with lumped-element grid.
>> I found application notes where in the examples they just shown the
>> calculated values, without describing the calculation.
>>
>> regards,
>> Istvan Nagy
>> ------------------------------------------------------------------
>> To unsubscribe from si-list:
>> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
>>
>> or to administer your membership from a web page, go to:
>> //www.freelists.org/webpage/si-list
>>
>> For help:
>> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
>>
>>
>> List technical documents are available at:
>> http://www.si-list.net
>>
>> List archives are viewable at:
>> //www.freelists.org/archives/si-list
>> or at our remote archives:
>> http://groups.yahoo.com/group/si-list/messages
>> Old (prior to June 6, 2001) list archives are viewable at:
>> http://www.qsl.net/wb6tpu
>>
>>
>>
>>
>
>
> --
> Steve Weir
> Teraspeed Consulting Group LLC
> 121 North River Drive
> Narragansett, RI 02882
>
> California office
> (866) 675-4630 Business
> (707) 780-1951 Fax
>
> Main office
> (401) 284-1827 Business
> (401) 284-1840 Fax
>
> Oregon office
> (503) 430-1065 Business
> (503) 430-1285 Fax
>
> http://www.teraspeed.com
> This e-mail contains proprietary and confidential intellectual property of
> Teraspeed Consulting Group LLC
>
----------------------------------------------------------------------------
--------------------------
> Teraspeed(R) is the registered service mark of Teraspeed Consulting Group
> LLC
>
> ------------------------------------------------------------------
> To unsubscribe from si-list:
> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
>
> or to administer your membership from a web page, go to:
> //www.freelists.org/webpage/si-list
>
> For help:
> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
>
>
> List technical documents are available at:
> http://www.si-list.net
>
> List archives are viewable at:
> //www.freelists.org/archives/si-list
> or at our remote archives:
> http://groups.yahoo.com/group/si-list/messages
> Old (prior to June 6, 2001) list archives are viewable at:
> http://www.qsl.net/wb6tpu
>
>
>
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List technical documents are available at:
http://www.si-list.net
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List technical documents are available at:
http://www.si-list.net
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
