[SI-LIST] Dielectric loss modeling
- From: "Sogo Hsu" <sogo.hsu@xxxxxxxxxxx>
- To: si-list@xxxxxxxxxxxxx
- Date: Wed, 01 Dec 2004 04:00:34 -0000
Hi, Gurus,
One topic confused me for a long time, I look forward somebody here
can help me to clarify. To model the dielectric loss for trace, it
is used to express the conductance as
G(f) = G0 + freq * Gd
where G0 is in terms of leakage current loss at DC and Gd is
dielectric loss. As I know, Gd is expressed as
Gd = 2* pi * (tan delta) * C
where (tan delta) is loss tangent. and (tan delta) is defined as
conductivity / (2* pi * freq * epsilon). As a result,
G(f) = G0 + freq * (2*pi*(conductivity)/(2 * pi*freq*epsilon))*C
G(f) = G0 + (conductivity/epsilon) * C
My questions are
(1) Ideally, G0 is equal to (conductivity/epsilon) * C, as well as G
(f) is frequency independent variable! Is it right?
(2) Base on the definition, loss tangent is proportial to 1/freq.
However, we typically treated loss tangent as a constant versus
frequency. If loss tangent is a constant, it means conductivity is
proportion to frequency if we assumed epsilon is stable versus
frequency. Is it true regarding a constant loss tangent or a linear
frequency dependent conductivity? Or, both of them is wrong.
(3) We verify the extracted RLGC file against Hspice in v. 2004.09.
We found the Gd is exactly the half of above equation for Microstrip
line in inhomogeneous medium. The rsults for Stripline agree with
the above equation. It seems Gd for Microstrip line is the average
value of dielectric and free space area. It is reasonable? Does
anyone verify the same issue before?
Best regards,
Sogo Hsu, Ph. D.
Simulation center/Foxconn
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