FreeLists / si-list / [SI-LIST] Re: Curved vs. 90 degree PCB trace paper

[Scott McMorrow <scott@xxxxxxxxxxxxx>]

Chris

Eric Bogatin shows a simple method for approximation of the excess 
capacitance of a corner bend in his book Signal Integrity Simplifed, in 
section 8.16, which is correlated to measurements.

Gupta, et al, show some more formal approximations in the book, 
Microstrip Lines and Slotlines, and also shows some methods for 
compensation for the effect.

Corners are a big deal in low loss RF and Microwave circuit design when 
trace widths are often quite wide.  But, if you are using trace widths 
below 10 mils, and data rates below 10G, then it just doesn't matter, 
the discontinuity is just too small to matter ... unless you have a 
bunch of them and are trying to match skew to obscenely low tolerances.  
Then the difference in the number of bends in a trace delay meander may 
matter, although often hard to distinguish from the excess coupling 
capacitance in a meander.

Scott

Scott McMorrow
Teraspeed Consulting Group LLC
121 North River Drive
Narragansett, RI 02882
(401) 284-1827 Business
(401) 284-1840 Fax

http://www.teraspeed.com

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Teraspeed Consulting Group LLC



Chris McGrath wrote:

>Does anybody have the link to (or have a copy of) the research that
>somebody posted in the last year debunking the myth that 90 degree bends
>are bad- even into higher frequencies?  I went through the archives but
>was unable to find it.
>
>Thanks,
>Chris
>
>
>------------------------------------------
>Chris McGrath
>Sr. Hardware Engineer
>ADIC
>ph: (607) 241-4858
>eM: chris.mcgrath@xxxxxxxx
>------------------------------------------
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