Re: Link Status thoughts
Ed,
Ed Grivna wrote:
>
> 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.
>
By this, do you mean the PMA receive? The PCS receive is the
XSBI bus and the PMA would drive that to the appropriate voltage
levels whether it had a strong signal at its inputs or a weak one.
Ben
> 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@amcc.com
> > > -----------------------------------------
> > >
> > >
--
-----------------------------------------
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@amcc.com
-----------------------------------------