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Re: [BP] how to evaluate signaling method follow up



Hi All,
Crosstalk is still a propagation phenomenon. So in terms of the
propagation constant gamma, what do you think beta should be a DC? The
answer should lend insight to what is physically correct.

... Rich

-----Original Message-----
From: owner-stds-802-3-blade@listserv.ieee.org
[mailto:owner-stds-802-3-blade@listserv.ieee.org] On Behalf Of Graeme
Boyd
Sent: Friday, September 10, 2004 7:04 AM
To: STDS-802-3-BLADE@listserv.ieee.org
Subject: Re: [BP] how to evaluate signaling method follow up

Brian

I always though it was related to the SNR of the VNA and very low amount
of coupling for that connection. However your statement about
AC-coupling sounds better. If so then shifting the curve to 90 degrees
would be correct thing to do would it not?

I will look at some data to see if this makes sense.

Graeme

On Fri, 2004-09-10 at 03:17, Brian Brunn wrote:
> Hi Graeme,
>
> Could the reason the phase on crosstalk channels does not inherently
> extrapolate to 0 at DC, be due to the crosstalk channels being
inherently
> AC-coupled?
>
> If so, then I don't think we want to do the "shift the whole curve to
0 at
> DC" step.
>
> Brian
>
> p.s. getting inverted phase is a real puzzle.
>
>
>
> ----- Original Message -----
> From: "Graeme Boyd" <why@pmc-sierra.com>
> To: "Brian Brunn" <Brian.Brunn@xilinx.com>;
> <STDS-802-3-BLADE@listserv.ieee.org>
> Cc: <why@pmc-sierra.com>
> Sent: Wednesday, September 08, 2004 5:44 PM
> Subject: RE: [BP] how to evaluate signaling method follow up
>
>
> > Brian
> >
> > MAG=1 @ DC is clearly wrong especially for long channels due to
non-zero
> > resistance of the channel
> >
> > On the phase front really only have 2 options
> > 1) extrapolate linearly (as I indicated) and shifting the entire
curve
> > 2) extrapolate with DC = 0 and x number of the lower unwrapped phase
> > points say with spline curve fitting
> >
> > Of the two I have found the results appear to make more sense with
> > shifting the entire curve. Note that something clearly went wrong
with
> > the measurements if it does not linearly extrapolated to 0 at DC.
For
> > most cases I find that if one does a good calibration the amount you
> > have to shift the curve is on the order of 0.5 to 1 degree for the
> > forward channel. Now the cross talk channels do give rise to more
> > problems for some reason.
> >
> > As for getting inverted phase, I have seen this several times from
our
> > customers when they send me data. I assume this is happening due to
the
> > method of calibration and then flipping the cables for the real
> > measurement but really don't know for sure.
> >
> > Graeme
> >
> > On Wed, 2004-09-08 at 15:08, Brian Brunn wrote:
> >> Hi Graeme,
> >>
> >> Thanks.
> >>
> >> I agree with the magnitude.  I've seen people use MAG=1 @ DC which
is
> >> painful.
> >>
> >> On the phase, it appears to me that phase delay (not group delay)
is our
> >> quantity of interest so I am leery about shifting the whole phase
curve.
> >>
> >> Do you know how measured s-parameters can result in inverted phase?
> >>
> >> Brian
> >>
> >>
> >>
> >> -----Original Message-----
> >> From: Graeme Boyd [mailto:why@pmc-sierra.com]
> >> Sent: Wednesday, September 08, 2004 4:29 PM
> >> To: Brian Brunn
> >> Cc: why@pmc-sierra.com; STDS-802-3-BLADE@listserv.ieee.org
> >> Subject: Re: [BP] how to evaluate signaling method follow up
> >>
> >> Brian
> >>
> >> How about this.
> >>
> >> - For magnitude part:
> >>   - Extrapolation toward DC linearly based on at least the lowest 5
> >> measured points
> >>
> >> - For phase part:
> >>   - Extrapolation toward DC linearly on the unwrapped phase based
on at
> >> least the lowest 5 measured points
> >>   - Shift the entire curve such that the point at DC has 0 degrees
> >>   - If required invert the curve so that the unwrapped phase
decreases
> >> with increasing frequency
> >>
> >>
> >> Also of note if one is going to use S-parameters within Hspice we
have
> >> found that one needs to have linearly spaced frequency steps
starting at
> >> DC and going to at least 3x baud rate (for NRZ) to get similar
results
> >> with ADS or MATLAB.
> >>
> >> Graeme
> >>
> >> On Thu, 2004-09-02 at 08:49, Brian Brunn wrote:
> >> > All,
> >> >
> >> > On todays call there were references to the need to "properly"
> >> > extrapolate
> >> > measured s-parameter data down to DC in order to generate
accurate
> >> > pulse
> >> > responses.  It appears for signalling evaluation, we need to
agree on a
> >> > common method.
> >> >
> >> > Is anyone interested in making a proposal?
> >> >
> >> > Brian Brunn
> >> > Xilinx
> >> >
> >> >
> >> >
> >> > -----Original Message-----
> >> > From: owner-stds-802-3-blade@listserv.ieee.org
> >> > [mailto:owner-stds-802-3-blade@listserv.ieee.org]On Behalf Of Ali
> >> > Ghiasi
> >> > Sent: Thursday, September 02, 2004 10:50 AM
> >> > To: STDS-802-3-BLADE@listserv.ieee.org
> >> > Subject: Re: [BP] how to evaluate signaling method follow up
> >> >
> >> >
> >> > Mike
> >> >
> >> > Attach is the pulse response I get for the IEEE thru_rev5 model,
I was
> >> > referring to the ripple prior to
> >> > main pulse.
> >> >
> >> > Thanks,
> >> > Ali
> >> >
> >> > Mellitz, Richard wrote:
> >> >
> >> > >I added the shell for package modeling that I've been using for
some
> >> > >time now. I just call it the spec package models that I use to
driver
> >> > >real design requirement. I just tuned the models to -10dB for
the 5GHz
> >> > >and under mark. It's under 100 MB too :-)
> >> > >
> >> > >Anyhow it's a 3 differential line model and assumes the die
resistance
> >> > >and capacitance load are parameters in the die model outside of
this
> >> > >package model.
> >> > >
> >> > >
> >> > >PS, Oh Charles,
> >> > >Neat hspice tricks! It addresses channel jitter amplification.
> >> > >
> >> > >
> >> > >-----Original Message-----
> >> > >From: owner-stds-802-3-blade@listserv.ieee.org
> >> > >[mailto:owner-stds-802-3-blade@listserv.ieee.org] On Behalf Of
Charles
> >> > >Moore
> >> > >Sent: Wednesday, September 01, 2004 7:23 PM
> >> > >To: STDS-802-3-BLADE@listserv.ieee.org
> >> > >Subject: [BP] how to evaluate signaling method follow up
> >> > >
> >> > >
> >> > >guys,
> >> > >
> >> > >    Here is the next step after the proposal i sent out August
23.
> >> > >
> >> > >    This includes:
> >> > >
> >> > >    1.  A simulation file for NRZ simulation.
> >> > >
> >> > >    2.  A transmitter subcircuit file for NRZ simulation.
> >> > >
> >> > >    3.  A simulation file for PAM4 simulation.
> >> > >
> >> > >    4.  A transmitter subcircuit file for PAM4 simulation.
> >> > >
> >> > >    5.  a zip file with the PRBS pwl files i used.
> >> > >
> >> > >    You can look at the files to see the structure of the
simulation
> >> > > or
> >> > >use them to do simulations yourself.  If you want to do
simulations
> >> > >you will need:
> >> > >
> >> > >    1.  A receiver subcircuit file named "rx.inc".  I am
treating
> >> > >        receivers as proprietary.
> >> > >
> >> > >    2.  Package model subcircuit files for the transmitter
called:
> >> > >        "TxPackage.inc" and for the receiver called:
"RxPackage.inc"
> >> > >
> >> > >    3.  A touchstone file describing the channel.  You may need
to
> >> > >        change the name of the file in the simulation file.
> >> > >
> >> > >     You may want to change the parameter values in the
simulation
> >> > > file.
> >> > >The tap values i have included give fairly good EYEs with Steve
> >> > >Anderson's thru6 channel and the stresses nearly or just
re-close the
> >> > >EYE.
> >> > >
> >> > >    The over all structure of the simulation deck for either is:
> >> > >
> >> > >    The simulation file includes:
> >> > >
> >> > >      1.  Parameter values, which are in 3 kinds:
> >> > >        A.  Transmitter definition parameter:
> >> > >            i.   baud, baud rate:  10.3125G for NRZ or 5.15625G
for
> >> > > PAM4
> >> > >            ii.  Amp, the nominal peak to peak differential
amplitude
> >> > >            iii. Trf, the trapezoidal rise and fall time in UI
> >> > >        B.  Transmitter peaking parameters:
> >> > >            i.   1 Precursor and 1 postcursor tap value for NRZ
> >> > >            ii.  2 Postcursor tap values for PAM4
> >> > >        C.  Stress parameters:
> >> > >            i.   XtalkAmp, interference amplitude (half peak to
peak)
> >> > >            ii.  XtalkFratio, ratio of interference frequency to
> >> > >                 baud rate.
> >> > >            iii. TJ, total jitter in UI
> >> > >            iv.  dutyCycle_over_TJ, fraction of total jitter
which is
> >> > >                 at half baud rate
> >> > >    2.  Transmitter sub circuit.  The transmitter sub circuit
> >> > > implements
> >> > >        a 3 tap equalizer and includes parameterized jitter.
> >> > >    3.  Package models.  I am going to ask that someone else
find a
> >> > >        suitable model.
> >> > >    4.  The channel.
> >> > >    5.  Receiver load (the Tx load is included in the
subcircuit)
> >> > >    6.  Interference injection sources.
> >> > >    7.  An instance of the receiver sub circuit.  Someone else
should
> >> > >        provide the receiver model.  It may be encrypted.  The
Out
> >> > >        port or the MSB and LSB ports should be considered the
> >> > >        final measurement point.
> >> > >
> >> > >     If we decide to proceed with this approach the following
will
> >> > > need
> >> > >to be done before going too much farther:
> >> > >
> >> > >     1.  Define standard values for Transmitter definition
parameters
> >> > >         and targets for Stress parameters.  These may be
different
> >> > > for
> >> > >         the 3 (or more) signaling schemes.
> >> > >     2.  Find a  set of channels to simulate over.
> >> > >     3.  Write scripts for analyzing the output including
finding
> >> > >         EYE size if that is relevant and checking for correct
data.
> >> > >     4.  Write scripts which pre-code PRBS data for duo-binary
or
> >> > >         write output analysis script to post-decode the data.
> >> > >     5.  Generate longer data files for more through testing.
The
> >> > >         included scripts should be good enough for finding the
right
> >> > >         equalizer settings etc. but we will want longer more
complex
> >> > >         patterns for final evaluation.
> >> > >     6.  Separate out all the parts of the simulation file which
are
> >> > >         design values (like tap values) from the specified
parts, and
> >> > >         put them in an include file.
> >> > >     7.  Fix the various problems which the ad-hoc will discover
for
> >> > >         me.
> >> > >
> >> > >                      charles
> >> > >
> >> > >
> >> > >
> >> >
>|--------------------------------------------------------------------|
> >> > >|       Charles Moore
> >> > >|       Agilent Technologies
> >> > >|       ASIC Products Division
> >> > >|       charles_moore@agilent.com
> >> > >|       (970) 288-4561
> >> >
>|--------------------------------------------------------------------|
> >> > >
> >> > >
> >>
> >>
> >
> >