[SI-LIST] Re: High Speed Termination
- From: "michael munroe" <mmunroe@xxxxxxxxxxxxxx>
- To: <hitendra.patel@xxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Mon, 12 Jul 2004 11:01:37 -0400
Hitendra,
A few historical comments/observations while we are all waiting for some
specific technical recommendations:
In the standard bus industry (VME,FB+ cPCI) the migration of termination
resister packaging was from soldered axial lead discrete termination
components, to socked discrete termination components to small form factor
SMT DIP resister networks. ESR characteristics of all capacitors used at
higher bus speeds became increasingly important.
I haven't seen discussion of the high-frequency characteristics of
termination resisters for backplanes, however for calibration structures
used for de-embedding measurements, this subject seems to generate a good
deal of discussion. The problem of designing a practical structure that has
the desired RCL behavior at data rates above 3 Gbps seems to be a non
trivial task.
Lastly, at the zenith of high bit width parallel multi-drop BTL
architectures (i.e. 256-bit Futurebus), just feeding power into the
termination networks efficiently enough to maintain switching voltage
tolerances became an unanticipated design problem (well unanticipated by
most with the exception of C.Michael Hayward).
Anyway, the di/dt requirements for those architectures resulted in a variety
of solutions. Luckily, the requirements of single ended differential fabrics
at LVDS voltages, made those di/dt problems go away from the standpoint of
power deliver, at least so far as I understand the problem. Now achieving
ideal termination to reduce reflections and therefore improve the available
noise margin seems to be driving the need to design termination structures
that have the desired behavior at these potentially blistering fast edge
rates.
Still waiting for a real answer,
michael munroe "A Copper Alliance;
Dedicated to Copper Pushing copper to its limits.
Bustronic Corp. Density, agility and efficiency."
804-240-7188 cell
www.bustronic.com
www.elma.com
www.copperalliance.net
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Hitendra Patel
Sent: Monday, July 12, 2004 9:11 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] High Speed Termination
Hello SI Experts!!
Just curious whether any one of you have/had experience SI problems pertain
to resistor termination due to its packaging or RCL effects. If yes, please
share your experience. Thank you and looking forward to read your feedback.
Regards,
Hitendra :-)
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