**From:** Ozgur Misman (*omism@amkor.com*)

**Date:** Fri Apr 27 2001 - 14:41:49 PDT

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Hi Nianci,

We faced a similar problem before. I would say that line cal is more

accurate then momentum for lossy characteristic impexdance. Momentum does

not model metal thickness. I think the upcoming version will. The

impedance you get using line cal is lossy characteristic impedance and that

matches very well with some state of the art 2-D field solver solutions. My

guess is you should be ok with momentum if lossles cjharacteristic

impedance sqrt (L/C) is what you are looking for. For lossy, I would go by

Line Cal.

Again, this is purely based on my personal experience and I haven't

verified it with measurement but used a 2-D solver for comparisons.

Best Regards,

Ozgur Misman

Amkor Technology, INC

Sr. Engineer

"Nianci Wang" <nwang@amcc.com>@silab.eng.sun.com on 04/27/2001 01:24:25 PM

Please respond to "Nianci Wang" <nwang@amcc.com>

Sent by: owner-si-list@silab.eng.sun.com

To: "'si-list@silab.eng.sun.com'" <si-list@silab.eng.sun.com>

cc:

Subject: [SI-LIST] : Question on transmission line simulation by HP ADS

/Momentum

Hi,

I have a question on simulating finite metal thickness transmission line by

using HP ADS Line Calc and Momentum.

Basically I did simulation by using both line Calc and Momentum for several

different structures, I found that Momentum always give me a higher

characteristic impedance than that of Line Calc. The thicker the metal is,

the

larger the difference between two simulation results. I did talk with HP

ADS

help line and got the answer was that Momentum gave more accurate

simulation

results. I wonder if any one did the simulation by each line Calc or

Momentum

and compared the result with that of the measurement.

Thank you

Nianci

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**Next message:**Mike Saunders: "[SI-LIST] : Re: Question on DDR dram DQS handling."**Previous message:**Ingraham, Andrew: "RE: [SI-LIST] : Clock Jitter"**Maybe in reply to:**Nianci Wang: "[SI-LIST] : Question on transmission line simulation by HP ADS /Momentum"**Next in thread:**Nianci Wang: "Re: [SI-LIST] : Question on transmission line simulation by HP ADS /Momentum"**Reply:**Nianci Wang: "Re: [SI-LIST] : Question on transmission line simulation by HP ADS /Momentum"

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