[SI-LIST] Re: Transmission Line Effect in PDN
- From: "Yuriy Shlepnev" <shlepnev@xxxxxxxxxxxxx>
- To: "'Rajan Hansa'" <all.si.list@xxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Tue, 5 Jul 2011 08:24:31 -0700
Rajan,
Analysis of PDNs can be formalized as a solution of 2D Telegrapher's
equations or 2D Helmholtz equation (or transmission plane equations). It is
a macro-model of a structure with two parallel closely spaced conductive
planes with a dielectric layer between them. 2D equations can be derived
from Maxwell's equations taking into account conductor and dielectric
dispersion and losses, similar to derivation of 1D Telegrapher's equations
for t-lines. The names similarity may imply similarity of the models, but
the equations are actually quite different. First of all, transmission plane
problem is 2-dimensional. It means that instead of the length parameter,
there are size and shape parameters. Instead of reflections at
discontinuities there are reflections of radial waves from boundaries and
via-holes for instance. Instead of terminations at two ends (or along the
line), there are terminations over some area with impedances of components,
decoupling capacitors and possible terminations at the plane edges. A design
goal for a t-line segment may be to transmit a signal with minimal
distortions - it can be formulated in terms of frequency-dependent
characteristic impedance and delay. Design goals for a PDN is to deliver
power and suppress unwanted interference over a given frequency range - it
can be formulated in terms of the input impedance at the location of a
component computed by solving 2D equations. This model includes all possible
wave effects in the transmission planes. It is technically not correct to
talk about transmission line effects in transmission planes used for PDNs.
We rather have to discuss the wave effects.
Note, that the planar problems formalized as 2D Telegrapher's or 2D
Helmholtz equations are also often used in microwave applications (see for
instance T. Okoshi, Planar Circuits for Microwave and Lightwaves,1985).
Though the design goals there may be different depending on where the planes
are used - in filters, splitters or dividers or antennas. The most recent
use of the parallel planes is to form substrate integrated waveguides, where
the design goals may be the same as for TEM transmission lines.
Yuriy Shlepnev
www.simberian.com
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Rajan Hansa
Sent: Tuesday, July 05, 2011 4:03 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Transmission Line Effect in PDN
Guys,
Can anyone explain that why don't we consider transmission line effects (
like reflection, length of line, termination of line ) in power delivery
network (PDN) analysis ?
Why in PDN all effort is to reduce PDN impedance and no one talks about
above mentioned transmission line effects ??
Rajan
------------------------------------------------------------------
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
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
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
