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

RE: XAUI IO specs


The Hari I/O spec's from the November meeting are differential p-p.  It's
always a confusing spec, but I would simplify it by saying that the
VoDif(max) of 800mV would be 400mV if measured single-ended p-p.  (In
essense, the swings are reduced by a little over one-half of the previous
differential PECL swings used in 1GbE.) 

In addition the interface is based on AC coupling so common mode voltage is
not necessary.


- Richard

> -----Original Message-----
> From: kdemsky@xxxxxxxxxx [mailto:kdemsky@xxxxxxxxxx]
> Sent: Monday, April 17, 2000 8:20 PM
> To: stds-802-3-hssg@xxxxxxxx
> Subject: Re: XAUI IO specs
> Rich,
> Thanks for the link to the presentation.  I have been looking for that
> presentation for a couple days.  It makes things clear to me.
> iasi_1_1199.pdf
> It looks like Ali did a fine job of defining signaling.  
> Looking at the
> LVDS levels in the table on page 12, it looks like no signals 
> are referred
> to a peak-to-peak need not be defined that way.  In fact the 
> first four
> items in the LVDS column match the IEEE spec.
> It appears by the data in the Hari column that it is a custom 
> I/O signaling
> level designed to launch 4x the power (2x voltage and 2x 
> current) into the
> trace, counting on attenuation of up to 9.1 dB with "normal" 
> FR4, and still
> having about the same signal as required at the receiver end 
> I also agree with the deviation from tight termination 
> tolerances in IEEE
> LVDS spec, allowing us to integrate the receiver termination 
> resistors.
> I also looked at the picture on Page 13 of Ali's proposal, 
> and noticed that
> you referred to the 0V in the picture as ground.  The 0V 
> above the X1 point
> is 0V differential and has nothing to do with ground.  Now my 
> head doesn't
> hurt any more.
> Kevin Demsky
> Mixed Signal and VLSI Development
> IBM Corp.
> 3605 Hwy 52 N
> Dept. QXS Bldg. 050-2
> Rochester, MN  55901
> Internal E-mail:  kdemsky@ibmusm07
> External E-mail:  kdemsky@xxxxxxxxxx
> Phone:  507-253-5799
> Fax:  507-253-4966
> >Mike,
> >On your P.S., I was referencing slide 13 from the proposal 
> authored by Mr.
> Ali
> >Ghiasi and Mr. Richard Dugan presented at the November '99 
> HSSG meeting in
> >Kauai, HI:
> >

>The legends on the Y-axis come from the table on slide 5. Note the
reference to
>0V, or ground on slide 13.

>Best Regards,