[SI-LIST] Re: Losses - 2.5Gbps on FR4
- From: "Dima Smolyansky" <Dima.Smolyansky@xxxxxxxxxxxxxx>
- To: <jeff_latourrette@xxxxxxxxxxx>, <dorin.oprea@xxxxxxxxxxx>
- Date: Tue, 29 Jul 2003 10:20:49 -0700
I have to agree with Jeff - with a couple of test traces, losses can be
extracted within seconds. See, for example, the paper on lossy line
simulation and analysis at our web site - www.tdasystems.com/support/. Most
relevant articles are Lossy Line Simulation and Analysis,
http://www.tdasystems.com/library/appnotes/siml-0203.pdf and Practical
Characterization of Lossy Transmission Lines Using TDR,
http://www.tdasystems.com/library/appnotes/loss0703.pdf
Thanks,
===================
Dima Smolyansky
TDA Systems, Inc.
4000 Kruse Way Place
Bldg. 2, Suite 300
Lake Oswego, OR 97035
(503) 246-2272
(503) 246-2282 (fax)
----- Original Message -----
From: <jeff_latourrette@xxxxxxxxxxx>
To: <dorin.oprea@xxxxxxxxxxx>
Cc: <si-list@xxxxxxxxxxxxx>
Sent: Tuesday, July 29, 2003 9:01 AM
Subject: [SI-LIST] Re: Losses - 2.5Gbps on FR4
> Dorin:
> Sounds real to me, tand = 0.03 is pretty lossy material.
>
> Based on information provided, I also ran your scenario (in msec) on
Linecalc, part of Agilent's ADS, and got 5.5 dB power loss (for just the 30"
line) at 1.25 GHz ("fundamental" of switching frequency). Loss was 9.9 dB
at 2nd harmonic and 18.4 dB at 4th, which sounds very high, but seems to
compare well with Geoff's results.
>
> You shouldn't have to run 10 hours of simulation just to get losses,
although I'm sure there are other things you are after. You could simulate
(& measure to compare) an inch or two of FR-4 to get dB/inch.
>
> Experimental boards allowing different connector types and run lengths are
invaluable for this type of work.
>
> Some colleagues of mine at Agilent wrote a great paper on this at ONIDS
2002 .....
>
> The Path to 10 Gb/s:Connector and Backplane Capabilities for High-Speed
Applications
>
> http://literature.agilent.com/litweb/pdf/5988-7053EN.pdf
>
>
> Enjoy,
>
> Jeff LaT.
>
>
> -----Original Message-----
> From: Dorin [mailto:dorin.oprea@xxxxxxxxxxx]
> Sent: Tuesday, July 29, 2003 7:47 AM
> To: si-list
> Subject: [SI-LIST] Losses - 2.5Gbps on FR4
>
>
> Hi,
> The simulation I did shows 5dB voltage loss on 30" long interconnect on
> FR4 (tan loss 0.03) which includes 0.005" traces 0.5 oz. copper, one
> NexLev and two Metral connectors. Two pulses P/N, 2V with 50 ohm series
> were applied to the circuit and one 100 ohm resistor as a termination.
> Is this loss real? If not, can you tell what is the approximate
> deviation, just to get a feeling?
> I was told that hspice simulated losses are too optimistic and
> therefore, long traces should be chopped; if so, what would be the
> optimum segment length recommended for the loss simulation so that the
> simulation time is not excessively long (now I need over 10 hours on
> Linux LSF server).
>
> Thanks,
> Dorin
>
>
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