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Re: Link Status thoughts






Hi Howard,

part of what you suggest here makes sense, but I dissagree with 
a different part.

The part I don't like is the idea that the PCS receive should
have a bias to prevent chatter in an AC-coupled connection.  
I don't particularly like offset-biased differential connections
because they cause duty cycle distortion of the signal.

I think you suggested the best solution in your first paragraph;
i.e., that being to have the PCS receive also have a signal
detect (peak differential-amplitude detector) and to squelch the
line receiver if there is insufficient amplitude.

Regards,

Ed Grivna
Cypress Semiconductor

> 
> General comment:
> 
> Pins = Bad
> 
> I believe that the limiting amp stage should have a signal detect
> function built into it, and should squelch its output when the
> incoming signal is below the noise floor.
> 
> For AC coupled systems, this implies the addition of a bias to
> the PCS receive input so that it doesn't chatter when the
> PMD receive output is squelched.  The "flat line" state observed
> by the PCS receiver will be a sufficient indication of a dead link.
> 
> We can't rely on MDIO for signal detect reporting between the
> PMD and the PCS. We can rely on MDIO for Link Status (a superset
> of signal detect) reporting between the PCS and Station Management.
> 
> Howard Frazier
> DomiNet Systems, Inc.
> 
> Ben Brown wrote:
> > 
> > Hey,
> > 
> > After a discussion some of us had during the editorial
> > meeting yesterday, I thought I'd put some of our thoughts
> > down on paper. There are still quite a few questions
> > buried in these slides. Anyone with comments, please
> > feel free to share them. I'd like to have these comments
> > before the November meeting so we can put a proposal on
> > the table.
> > 
> > Thanks,
> > Ben
> > 
> > --
> > -----------------------------------------
> > Benjamin Brown
> > AMCC
> > 2 Commerce Park West
> > Suite 104
> > Bedford NH 03110
> > 603-641-9837 - Work
> > 603-491-0296 - Cell
> > 603-647-2291 - Fax
> > 603-798-4115 - Home Office
> > bbrown@xxxxxxxx
> > -----------------------------------------
> > 
> >