[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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