The main design problem with the interface
is not the ASIC but the switching noise impact
on the jitter performance of the XCVR PLL.
Currently all 2.5Ghz SONET XCVRs on the market
use 8 ir 16 bit diff LVDS interface. I am not
sure if it is possible to meet SONET jitter spec using
32 bit single ended interface.
By choosing a single ended interface
you limit your transmitter and receiver performance
and you limit the distance 10GBE can span.
I suspect that long distance 10GBE will have
to use a fully differential interface.
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