RE: XAUI Driver Spec
Boaz,
Will specifying eye opening require the prediction of noise and crosstalk
as well as jitter (some of the noise and crosstalk will show up as jitter,
some as DC offset)?
All will affect the eye, but may be very difficult to predict when
accounting for board material, connectors etc.
Also, how much distance will be lost by raising this receive level and
accounting for jitter in the number? A more sensitive receiver should easily
be able to recover the lower input levels. This will translate into low
crosstalk distance for the interface.
Gerry
-----Original Message-----
From: owner-stds-802-3-hssg@xxxxxxxx
[mailto:owner-stds-802-3-hssg@xxxxxxxx]On Behalf Of Boaz Shahar
Sent: Monday, November 06, 2000 1:02 AM
To: 'Ali Ghiasi'; Boaz Shahar
Cc: Robbie Shergill; stds-802-3-hssg@xxxxxxxx
Subject: RE: XAUI Driver Spec
I See.
The question is: the 200mv signal at the receiver inputs is the size of the
eye pattern (mesured under standard jitter conditions), or the value does
not include jitter.
Boaz
> -----Original Message-----
> From: Ali Ghiasi [mailto:aghiasi@xxxxxxxxxxxxx]
> Sent: Monday, November 06, 2000 4:15 AM
> To: Boaz Shahar
> Cc: Robbie Shergill; stds-802-3-hssg@xxxxxxxx
> Subject: Re: XAUI Driver Spec
>
>
>
> Hi Boaz
>
> The 900 mV is due to signal attenuation as FR4 are predominately
> loss limited.
>
> Thanks,
>
> Ali
>
> Boaz Shahar wrote:
> >
> > Hello Ali,
> > I have a question in regards to your presentation for Tampa:
> >
> > You assert that the 900mv signal is attenuated to 200mv due
> to a loss of
> > 13db. This loss includes Jitter? That is, the height of the
> eye pattern in
> > the receiver's input is 200mv or less then that due to jitter?
> >
> > Thx.,
> > Boaz
> >
> > > -----Original Message-----
> > > From: Ali Ghiasi [mailto:aghiasi@xxxxxxxxxxxxx]
> > > Sent: Friday, November 03, 2000 6:17 PM
> > > To: Robbie Shergill
> > > Cc: stds-802-3-hssg@xxxxxxxx
> > > Subject: Re: XAUI Driver Spec
> > >
> > >
> > >
> > > HI
> > >
> > > The receiver max amplitude need to be higher than
> transmitter to allow
> > > some
> > > margin and protection. Very likely in Tampa the max transmit
> > > amplitude
> > > will
> > > be raised, where 1.6 V max will become more logical. The
> 1.6 volts is
> > > p-p
> > > diff. so each wire only drives 800 mV.
> > >
> > > Thanks,
> > >
> > > Ali
> > >
> > > Broadcom
> > >
> > > Robbie Shergill wrote:
> > > >
> > > > Hello all,
> > > >
> > > > Last week in Austin the XAUI group decided to change Max
> > > Diff. Amplitude to
> > > > 1.6 volts. As I understood it, the rationale for increasing
> > > the max amplitude
> > > > was to achieve commonality with the Infiniband spec.
> > > Although I agree with
> > > > the spirit of this rationale, I checked the Infiniband spec
> > > and found
> > > > that they are trying to drive a cable as well as a
> > > backplane with one
> > > > electrical specification; thus the reason for the 1.6v
> spec. In this
> > > > case, I'm not sure if it is worth matching the Infiniband
> > > spec in this
> > > > one area. My feeling is that a driver circuit can be
> made to drive
> > > > up to either 1.0 volt or 1.6 volt relatively easily;
> but it would be
> > > > much more troublesome for a (XAUI) receiver to tolerate
> 1.6 volts
> > > > *needlessley*.
> > > >
> > > > So, if the above reasoning is agreed to by others, I would
> > > propose that we
> > > > stay with 1.0 volt max. diff. amplitude that is in the
> > > current draft 1.0
> > > > (page 119, line 22).
> > > >
> > > > -Robbie Shergill
> > > > National Semiconductor
> > >
>