Allow me to join the party and throw some results from Mentor HyperLynx Fast 3D
Solver. This is a 3D Quasi-Static field solver.
HyperLynx F3D @ 1GHz (extraction from a finite line segment):
L= 2.2988 nH/cm; C= 2.422 pF/cm; Zo= 30.81 Ohm
Hey Adnan,
You've received some great insights from others already... but to come at this
from a slightly different angle...
L_per_unit_length and C_per_ unit_length (and subsequent Zo) are essentially
*2D* characteristics that assumes "infinitely" long transmission lines...
You're essentially taking a *slice* out of it. Hence 2D cross-sectional
solvers (such as the one from Keysight and your Q2D and even others like Polar)
are natural to give you quick and accurate *2D* answers in the form that you
need.
But *3D* field solvers (like your Q3D and our F3D and even Yuriy's 3DTF...)
have to consider a finite, fully 3D, non-ideal structure (ie. imagine
discontinuities at the Ports) for its solution. Expect those tools to take
slightly longer to solve but it will give you accurate *3D* results. But you
will introduce some error when converting its *3D* results to some *2D*
characteristics if you are not careful to manage your *3D* simulation setup and
subsequent post-processing of its results.
But again, as all the wise people have already told you... talking with your
favorite vendor AEs will straighten it all out for you... That's what I do all
day long with my customers! ;-)
Regards,
Chase
___________________________________________________
Signal and Power Integrity | Mentor, A Siemens Business | Boston, USA
+1-508-565-8080
yun_chase@xxxxxxxxxx
https://support.sw.siemens.com/
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On ;
Behalf Of Yassin, Adnan
Sent: Thursday, September 3, 2020 6:46 PM
To: Stephen Slater <slater@xxxxxxxxxxxx>; CHARLES.GRASSO@xxxxxxxx;
shlepnev@xxxxxxxxxxxxx; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: ANSYS Q2D & Q3D Extracted L & C
Thanks all for your responses. What I am getting out of this is the numbers
from the 2D solver are more accurate (in line with results obtained by others).
Looks like 2D solvers are better suited for calculating TL impedance. I will be
checking with an application engineer to understand why 3D solver gave me
different inductance values.
Thanks,
-Adnan
-----Original Message-----
From: Stephen Slater <slater@xxxxxxxxxxxx>
Sent: Thursday, September 3, 2020 2:48 PM
To: CHARLES.GRASSO@xxxxxxxx; Yassin, Adnan <adnan.yassin@xxxxxxxxx>;
shlepnev@xxxxxxxxxxxxx; si-list@xxxxxxxxxxxxx
Subject: RE: [SI-LIST] Re: ANSYS Q2D & Q3D Extracted L & C
Hi Guys,
Probably worth mentioning that if you are trying to optimize the width of a
trace to get a certain impedance, then really all you need is a 2D
cross-sectional solver. A 2D cross-section is able to be meshed much more
finely than you would be practical for a 3D-FEM solver, and there are no ports
to setup.
Keysight ADS -> Controlled Impedance Line Designer gave me 30.61 Ohms for your
trace, 2.299nH/cm, 2.46pF/cm Very much in line with Simbeor and Q2D.
It took about 4secs to run, and took exactly the same amount of time to
optimize the width to give you 34 Ohms.
So - in summary use the right tool for the job - > T-line cross-section? Use
a 2D-cross-sectional solver. Got a T-line into a Via? use 3D-FEM.
Want to compare the accuracy of a 3D-EM tool to a 2D cross-sectional solver?...
if you need to, speak to your AE, because the setup of the problem in the 3D
tool matters.
Best regards,
Stephen.
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx <si-list-bounce@xxxxxxxxxxxxx> On Behalf Of
Grasso, Charles [Outlook]
Sent: Thursday, September 3, 2020 1:49 PM
To: Yassin, Adnan <adnan.yassin@xxxxxxxxx>; shlepnev@xxxxxxxxxxxxx;
si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: ANSYS Q2D & Q3D Extracted L & C
[EXTERNAL]
Q3D should be regarded as an LCR meter - so not really designed for
transmission line stuff.
I'd be interested in what your friendly Ansys rep says..!!
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx <si-list-bounce@xxxxxxxxxxxxx> On Behalf Of
Yassin, Adnan
Sent: Thursday, September 3, 2020 2:01 PM
To: shlepnev@xxxxxxxxxxxxx; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: ANSYS Q2D & Q3D Extracted L & C
This message originated outside of DISH and was sent by:
si-list-bounce@xxxxxxxxxxxxx
Thank you Yuriy and Ryan for your responses. I already opened a ticket with
ANSYS for App Engineer assistance. However, from your #'s (Yuriy), it seems I
was getting the correct values from Q2D.
BTW, I had a typo in my original message; Q3D (not Q2D) was giving me
L=11.112nH/cm.
Thanks,
-Adnan
-----Original Message-----
From: Yuriy Shlepnev <shlepnev@xxxxxxxxxxxxx>
Sent: Thursday, September 3, 2020 11:59 AM
To: Yassin, Adnan <adnan.yassin@xxxxxxxxx>; si-list@xxxxxxxxxxxxx
Subject: RE: [SI-LIST] ANSYS Q2D & Q3D Extracted L & C
Hi Adnan,
As Ryan pointed out, support may answer your questions, Though, this is good
test and here are more numbers for your problem (assuming resistivity of metal
1.724e-8 Ohm*m):
Simbeor SFS @ 1 GHz (quasi-static - cross-section):
L= 2.3097 nH/cm; C= 2.458 pF/cm; Zo= 30.76Ohm; Simbeor 3DTF @ 1 GHz (3D EM -
extraction from line segment):
L= 2.3208 nH/cm; C= 2.493 pF/cm; Zo= 30.63Ohm;
Best regards,
Yuriy
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On ;
Behalf Of Yassin, Adnan
Sent: Thursday, September 3, 2020 11:03 AM
To: si-list@xxxxxxxxxxxxx
Cc: Yassin, Adnan
Subject: [SI-LIST] ANSYS Q2D & Q3D Extracted L & C
Hi,
I have a trace 30um wide, with a thickness of 10um. It is a stripline with
dielectric thickness of 18um above and below the trace. The dielectric
coefficient is 4.5. Running these numbers through a tool on-line for impedance
calculations gives me slightly different numbers for L & C than ANSYS Q2D, but
totally different "L" number than ANSYS Q3D! Here is a summary of my data:
Online Calculator: L=1.888nH/cm, C=2.648pF/cm, and Zo&.704Ohm
ANSYS Q2D (@ 1GHz): : L=2.311nH/cm, C=2.508pF/cm, and Zo0.43Ohm
ANSYS Q3D (@ 1GHz): : L.112nH/cm, C=2.346pF/cm, and Zo=??
My questions:
1. Why "L" is much higher in Q3D compared to Q2D and the calculator? Is this
different inductance than what is reported by the latter two (e.g., loop
inductance vs. self inductance!)?
2. Can Zo in Q3D be calculated directly from these reported numbers by
applying the equation "SQRT(L/C)" or do I need to do some processing to "L"
first? Applying the equation to the #'s obtained above will give
SQRT(11.112nH/2.346pF)h.82Ohm, which is not realistic for my stackup (too high)!
Thanks,
-Adnan
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