Re: [10GBASE-CX4] Xmt Level
Steve,
I agree with Shawn. As I stated already I have seen multiple devices
from different vendors that can reach the 800mVppd level.
Howard
"Rogers, Shawn" wrote:
>
> Steve, we do not see a problem with 800mVp-p differential at 130nm using no
> special tricks or transistor construction. Our 130nm process is pretty
> generic so I would suggest that the issue is not the amplitude.
>
> I would prefer to leave the xmt amplitudes as is.
>
> BTW, most, if not all, 130nm processes require multiple supplies for
> backward I/O compatibility, so the point of adjusting this spec to allow a
> single supply device is not valid. I'd like to have a single supply device
> too, but the fact remains that I/O voltage levels always lag process
> technology. This dictates a world of where IC's have multiple supplies.
>
> Regards,
> Shawn
>
> ____________________________________________
> Shawn Rogers, PMP s-rogers@ti.com
> High Speed Serial Link Marketing
> Texas Instruments
> 12500 TI Boulevard / M/S 8732/ Dallas, Texas 75243
> Office: 214.480.2678 Cell: 214.549.4868
> ______________________________________
>
>
> -----Original Message-----
> From: Dreyer, Steve [mailto:steve.dreyer@intel.com]
> Sent: Friday, January 03, 2003 10:15 AM
> To: stds-802-3-10GBCX4@ieee.org
> Subject: RE: [10GBASE-CX4] Xmt Level
>
> Howard,
>
> The process you are using is probably different than ours,
> that is why we get different results. But we have seen
> 800mV being difficult to impossible on on 2 different processes.
> So, I would make the claim that it is a real issue that others
> could experience as well.
>
> And lowering the amplitude by 50mV is not that big a deal for the
> receiver.
>
> Using thick ox devices is not a very good solution because
> it requires a higher supply, which means more power, and now the
> IC requires dual power supplies.
>
> Our customers want a single 1.2V supply and low power. I think if
> lowering the level by 50mV can make this achievable by everyone,
> that is a big plus.
>
> Steve
>
> > -----Original Message-----
> > From: Howard A. Baumer [mailto:hbaumer@broadcom.com]
> > Sent: Friday, January 03, 2003 8:08 AM
> > To: Dreyer, Steve
> > Cc: stds-802-3-10GBCX4@ieee.org
> > Subject: Re: [10GBASE-CX4] Xmt Level
> >
> >
> > Steve,
> > There areexisting 130nm parts that put out > 800mVppd.
> > Our simulations
> > for our designs shows that this is possible. For the 90nm process a
> > designer can use the higher voltage fets to achieve even a 1 or 1.2V
> > output. Yes these fets are slower than the stnadard fets of 90nm but
> > they will be faster than the stnadard fets for 130nm.
> >
> >
> > Howard
> >
> >
> > "Dreyer, Steve" wrote:
> > >
> > > 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
> >