Thread Links Date Links
Thread Prev Thread Next Thread Index Date Prev Date Next Date Index

Re: 16-bit 625Mbaud XGMII

JR Rivers wrote:
> How about 1.25 Gbaud LVDS?

On the one hand, the telecom sector is going to LVDS in a very
big way.  Which means that all of those spiffy medium-interface
suppliers will be happy with it.

On the other hand, LVDS is utterly horrid for CMOS.  Locking
in a 2.4v common-mode range for as far as the eye can see is
a death sentence for I/O performance scaling.

> At 03:07 PM 3/20/00 -0800, Andreas Bechtolsheim wrote:
> >Jaimie: you need to count package pins, not signal I/Os.
> >
> >Your 625 MHz XGMII using LVDS differential signalling
> >requires 76 pins, which is the same pincost as the
> >312.5 MHz XGMII using single-ended drivers.
> >
> >In addition, you would need to run at least part of
> >your logic at the 625 MHz which is significantly
> >more difficult to implement than staying with a
> >clock frequency of 312.5 MHz.
> >

D. C. Sessions