[10GBASE-CX4] Xmt Level
Howard,
My comment to your comment to my comment below.
Steve
> "Dreyer, Steve" wrote:
> >
> > Howard,
> >
> > Took a quick look at the proposed draft and have the following
> > top level comments:
> >
> > 1. The min xmt amplitude of 800mV is probably not doable on a
> > chip with 1.2V only supply when all worst case conditions are
> > considered, it probably needs to be dropped another 50mV
> > or so. I plan to have a quick presentation showing
> > this next week. For reference, the min XAUI level is
> > a lot lower than 800mV using the far end method.
>
> <HAB>
> The 800mVpp is for a differential signal so that is
> only a 400mV single
> ended swing at the driver output, this is attainable with a 1.2V
> supply. Also the 800mVpp min is not the minimum the driver
> puts out, it
> is the minimum for the lower limit of the peak in the transmit output
> template you reference in #3 below. This will have to be
> clearified in
> the text.
> <HAB>
>
<SD>
Our simulations show that 800mV dif pp (or 400mV single ended) can't
be done at 1.2V when worst case conditions are put in place. We have
simulated with both a 130nm and 90nm process.
Propose we reduce the min level a bit based on these simulation to
maybe 750mV (will have exact number next week).
The 750mV is still larger than current XAUI min (if far
end spec is used), and reducing xmt level by 50mV reduces receive
sensitivity by 5mV, not a big impact on receive.
I plan to show simulation results next week at Vancouver. Maybe we
should wait until then to discuss further.
Steve