[SI-LIST] series term + fanout = noise?

Dear List:

        I just read a very nice presentation.  Most of it was educational and I
believe it.  One particular thing I really wonder about.
        Assume a fine pitch IC (0.5mm) with ordinary TTL/CMOS output (not 
something
differential or exotic), and resistor or ferrite packs for series
termination close to the IC.  They assert that if the R-packs have the same
pitch as the IC, it will make less noise.  If the IC must have fanout to
match the pitch of a slightly coarser Rpack, there will be more noise.
        I unfortunately don't get it.  The extra trace length before the series
termination is going to be pretty small--we're not talking about fanout to
fit 1/4W through-hole resistors.  And then after the R-pack, nothing can be
assumed about the trace length other than it must be reasonable for series
termination; the total length could be large compared with the tiny fanout
or stub.
        It should be noted that the presentation authors manufacture extra fine
pitch ferrite packs and SMD beads.
        Can somebody explain this?

Boris

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