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Re: [BP] how to evaluate signaling method


Charles,
We don't consider Hspice to be viable for simulating the complexities of high speed DFE based receivers.  We don't even attempt to build the models anymore.  Same is getting to be true for transmitters with latest FFE capabilities.

Thanks,        Joe


Joe Abler                                                             abler@us.ibm.com
IBM Microelectronics Division                          919-254-0573
Technical Marketing & HSS Applications    919-254-9616 (fax)
3039 Cornwallis Road                                                                
Research Triangle Park, NC  27709


Charles Moore <charles_moore@AGILENT.COM>
Sent by: owner-stds-802-3-blade@LISTSERV.IEEE.ORG

08/24/2004 04:40 PM
Please respond to Charles Moore

       
        To:        STDS-802-3-BLADE@LISTSERV.IEEE.ORG
        cc:        
        Subject:        Re: [BP] how to evaluate signaling method



yakov,

   1.  The hspice simulations i am talking of are time domain (TRAN)
       and take a fair amount of time.  Each simulation will be done
       with a single interference frequency.  Since the simulations
       take time we would like to minimize the number of frequencies
       used.  Measurements we have done here at Agilent indicate that,
       at least for the cases we have looked at, interference tolerance
       is fairly independent of frequency.

   2.  The cut-off of the cross talk will be the sum of 2 terms:

       1.  The upper bound of the Xtalk given the channel and Tx
           specs.  Here Xtalk is treated as a bounded random
           quantity.

       2.  A multiple of the expected RMS receiver input noise.
           The multiplier is chosen to give an agreed on BER.

                     charles


> Dear Charles,
>
>      Your idea of the signal evaluation seems to be  both novel and
> extremely attractive.
>
> 1) I assume in verifying  the model of cross talk vs, frequency using your
> proposed methodology it would be more effective to use several frequencies
> rather than a continuos spectra.
> In other words, the hspice model will provide the model for all frequencies
> of interest i.e. 30 MHz to 6.5 GHz while the actual tests will be done for
> e.g. , 30, 100, 500, 1000, 2000, 4000, 6500 MHz
>
> 2) Also, the cut-off of the cross talk will be given as the level where BER
> rate increases to 10 E -14 or  other  agreed number.
>
>  Is it so?
>
>
> Best Regards
> Yakov  Belopolsky
>
> yakov.belopolsky@foxconn.com
> TEL. 717-558-7518 ext. 103
> FAX 717-558-9306
>
>
>
>
>                     Charles Moore
>                     <charles_moore@AGILENT.COM>          To:     STDS-802-3-BLADE@listserv.ieee.org
>                     Sent by:                             cc:
>                     owner-stds-802-3-blade@listser       Subject:     [BP] how to evaluate signaling method
>                     v.ieee.org
>
>
>                     08/23/2004 06:11 PM
>                     Please respond to Charles
>                     Moore
>
>
>
>
>
>
> guys,
>
>     What i propose for signaling evaluation is an extension of
> ideas i presented at the July meeting in Portland in the talk
> "Receiver Testing Using Interference Tolerance Measurements".
>
>     The basic idea is to do a time domain simulation of the Tx,
> channel, and Rx using a standard, generally available simulator.
> To provide a simple and reproducible model of cross talk, a
> sinusoidal interfering signal will be added at the input to the
> receiver.  The amplitude of the interfering signal will be
> increased until the signal at the output of the Rx is deemed to
> be no longer usable.  The highest level of interference at which
> the Rx provides a usable output will be called the interference
> tolerance.  If the interference tolerance is below a specified
> (and perhaps signaling method dependent) value the simulated data
> path is non-compliant.  If the interference tolerance is above
> the specified value, it is compliant and has a margin which is
> equal to the difference between the simulated tolerance and the
> spec.  In general more margin is better.
>
>     This is the basic idea.  Details which i suggest be adopted as
> part of the method but which can be changed without altering the
> basic idea include:
>
> 1.  Use hspice as the simulator.
>
> 2.  Model the transmitter as:
>      a.  1 or 2 piecewise linear (PWL) current sources:
>          i.   1 current source with NRZ encoded data for NRZ signaling.
>          ii.  1 current source with precoded data for duo-binary
>               signaling.
>          iii. 2 current sources with 1/3 and 2/3 NRZ amplitude with LSB
>               and MSB data respectively, for PAM4 signaling.
>      b.  Rise times of PWL current sources set at about 30ps for NRX or
>          duo-binary or 60ps for PAM4
>      c.  R,L,C network between current source and Tx pins to provide
>          reasonable return loss vs frequency
>
> 3.  Include signaling method dependent Tx equalization in PWL current
>      source model.  Control equalization with hspice parameters.
>
> 4.  Include some modeled Tx Jitter in PWL current sources.
>
> 5.  Use hspice S-parameter network modeling capabilities to model
>      channel.
>
> 6.  Allow proprietary Rx models by Encryption.
>
> 7.  Add interference signal at Rx with sinusoidal current source.
>
> 8.  Allow for Rx input noise in the minimum interference tolerance spec.
>
> 9.  Determine that the Rx provides a usable output by:
>      a.  showing that data out of Rx gives the correct bits.
>      b.  If Rx does not include re-clocking, show that output eye is
>          wide enough
>      c.  If Rx does not include a limiting stage, show that the output
>          eye has enough amplitude.
>
> 10. Use 127 bit long PRBS pattern for data.  Offset a few bits between
>      pattern for MSB and LSB to give PAM4 pattern or use shorter PRBS
>      pattern for LSB.  Repeat PRBS pattern at least 4 times to allow
>      interference to "walk through" the data.
>
> 11. Test with more than one interfering rate.  Interesting rates
>      should include:
>      a.  For NRZ or PAM4, (1+.2/127)*(baud rate)/2
>      b.  For duo-binary, (1+.2/127)*(baud rate)/4
>
>                   charles
>
> --
> |--------------------------------------------------------------------|
> |       Charles Moore
> |       Agilent Technologies
> |       ASIC Products Division
> |       charles_moore@agilent.com
> |       (970) 288-4561
> |--------------------------------------------------------------------|
>
>
>
>