[SI-LIST] Re: Trace Width @ 3Gb/s

Interesting ... we've got two arguments going.  One that the problem is
a DC level shift caused by being AC coupled.  The other that it is high
frequency attenuation due to skin effect and/or dielectric loss.  The
first says it's a high-pass, the other that it's a low-pass.  Both
effects cause ISI.

You say the error occurs *at* the first 1 after a string of 0's.  If the
problem is only DC wander, then I would think the error would happen on
one of those 0's, or maybe the next 0 after the 1; but the 1 itself
should come through very reliably.  But if you see that the 1 itself is
too weak, then I think it looks more like HF attenuation.  The bit rate
exceeds the bandwidth.  That could be skin effect, dielectric, or
impedance discontinuities (i.e. pads, connectors).

Regards,
Andy



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