Ray,
Actually, signal integrity and EMI are related. Poor signal integrity means lots of EMI and vice versa. Control board-level EMI and you help control signal integrity.
Read the article from Doug B. Impedance mismatch won't become an issue until you reach several GHz, if it has any at all. The distortion you mention will typically be generated by poor impedance matching between outputs and inputs, not so much as the effect of sub milli-ohms in impedance change at a 45degree corner vs. a 45 or 90 degree arc. (The change in R, L, and C are miniscule and have little if no effect at the frequencies of interest. Photoplotted corners are typically rounded, so the change in width at that point is, what, 5% additional?) This distortion can be reduced by the use of termination Rs or keeping traces below critical length, to mention a couple of techniques.
Hey , I'm going to climb out on a limb here... does somebody there already have a preference of arc over "linear", and you're being forc... er, persuaded, to use arcs?
Use of arcs may be well suited for sensitive *analog* signals at high frequencies, but is not necessary for your frequencies of interest. Take a look at the motherboard in your computer and see how they route traces. All the motherboards in any computer I've owned have been routed with diagonal corners.
Sincerely,
Roger M. Stoops, CID+
Trimble Navigation Ltd., Dayton, OH, USA
Ph: +01 937.245.5288
Fax: +01 937.233.7511
-----Original Message-----
From: DesignerCouncil [mailto:[log in to unmask]]On Behalf Of Ray
Dwyer
Sent: Wednesday, December 17, 2003 12:08 PM
To: [log in to unmask]
Subject: [DC] Miter Routes again
Greetings Council,
Thanks for your input on this matter of arch versus linear miters.
Thanks Roger, I went to the web site you recommended,
http://www.ultracad.com/90deg.pdf
and will study the article.
My concern is signal integrity more than EMI. Things like does linear, more
so than arch, degrade the impedance of the trace or does it create
reflection points or does linear miters distort the square waves, like
spikes at the lead edges or ripple across the top, at frequencies around 200
MHz plus or minus a few hundred MHz's.and at what frequency does it become
an issue?
Ray
Greetings and Merry Christmas Ya'll,
At what point does an arch miter have better performance than linear miter?
And where can I read up on this subject.
I don't have access to anything like P-Spice.
I generally design to high speed digital signals.
Ray Dwyer
972-371-4046
Maxim
4401 Beltwood Parkway
Dallas, Tx. 75244
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