[time-nuts] An Excellent Tutorial on Precision Clocks
Dr Bruce Griffiths
bruce.griffiths at xtra.co.nz
Thu Mar 15 02:18:59 EDT 2007
Matt Ettus wrote:
> I was just investigating this very issue. It seems that every program
> you use to compute these impedances comes up with different answers,
> sometimes wildly different. Anyone have a free program they trust
> with this sort of thing?
> On 3/14/07, Dr Bruce Griffiths <bruce.griffiths at xtra.co.nz> wrote:
>> Tom Clark, K3IO wrote:
>>> I just stumbled on an excellent tutorial on low-noise clocks --
>>> National Semiconductors free downloadable "Clock Conditioner
>>> Owner's Manual". This 88 page document is a 3.7 MB PDF.
>>> 73 de Tom, K3IO
>>> 1. http://www.national.com/appinfo/interface/files/clk_conditioner_owners_manual.pdf
>>> time-nuts mailing list
>>> time-nuts at febo.com
>> Not bad except they give inaccurate formulae for stripline and
>> microstripline characteristic impedance.
>> Will these inaccurate formulae ever go away?
>> They've been around since the 1970's.
>> When with the trace widths and board thickness then in use the accuracy
>> wasn't too bad.
>> However they are not very useful for modern PCB design.
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The formulae given in Johnson and Graham's "High speed Digital Design"
However there's no substitute for measurement to check your calculations,
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