[SI-LIST] Re: WG: Transmitter Jitter Setup for simulations of 5Gbps SERDES

  • From: Siddharth Rajagopalan <maxsidhu@xxxxxxxxx>
  • To: "Havermann, Gert" <Gert.Havermann@xxxxxxxxxxx>
  • Date: Tue, 25 Jun 2013 17:30:38 +0530

hi gert,
 can't we subtract the bounded jitter (UBHPJ) and DCD from the total jitter
and utilize the rest for RJ (RMS) based on their corresponding BER value??
i was of the understanding that UBHPJ does not exhibit any correlation with
the data sequence but is periodic in nature and hence it should be entered
in PJ column and not RJ.
Regards,
Siddharth Rajagopalan
Signal integrity engineer,
Cisco systems
Mobile: +91 725 9277122
direct: +91 8044266229
official email: sidrajag@xxxxxxxxx




On Tue, Jun 25, 2013 at 5:24 PM, Havermann, Gert <Gert.Havermann@xxxxxxxxxxx
> wrote:

> Resent
>
> Von: Havermann, Gert
> Gesendet: Dienstag, 25. Juni 2013 13:48
> An: 'Siddharth Rajagopalan'
> Cc: si-list@xxxxxxxxxxxxx
> Betreff: AW: [SI-LIST] WG: Transmitter Jitter Setup for simulations of
> 5Gbps SERDES
>
> Hi Siddharth,
>
> you are correct, but where else to put it in when you only have bounded TX
> Jitter settings? This was the best compromise I could find. As I said, I
> know the results will not be precise, but that is usually not expected for
> simulations using generic Models. For accurate results you need to work
> with the AMI Models of the chosen Chipsets as they (should) include all the
> correct Jitter.
>
> BR
> Gert
>
> Von: Siddharth Rajagopalan [mailto:maxsidhu@xxxxxxxxx]
> Gesendet: Dienstag, 25. Juni 2013 13:43
> An: Havermann, Gert
> Cc: si-list@xxxxxxxxxxxxx
> Betreff: Re: [SI-LIST] WG: Transmitter Jitter Setup for simulations of
> 5Gbps SERDES
>
> hi gert,
> how can you enter the Uncorrelated bounded high probability jitter(UBHPJ)
> in RJ?? RJ by definition is an unbounded jitter. correct me if i am wrong.
>
>
> Regards,
> Siddharth Rajagopalan
> Signal integrity engineer,
> Cisco systems
> Mobile: +91 725 9277122
> direct: +91 8044266229
> official email: sidrajag@xxxxxxxxx
>
>
> On Tue, Jun 25, 2013 at 4:31 PM, Havermann, Gert <
> Gert.Havermann@xxxxxxxxxxx> wrote:
> Resent
>
> Von: Havermann, Gert
> Gesendet: Dienstag, 25. Juni 2013 12:50
> An: 'Hirshtal Itzhak'; si-list@xxxxxxxxxxxxx
> Betreff: AW: Transmitter Jitter Setup for simulations of 5Gbps SERDES
>
> Hi Itzhak,
>
> I think both isn't absolutely correct. The right in the definition of
> total Chip jitter is, it contains all Jitter aspects including ISI within
> the chip and package. You Channel will have additional ISI, but that's not
> part of the transmitter specification (or at least shouldn't be).
> As you know, I'm not using Hyperlynx. ADS asks for DCD, Clock DCD, PJ (in
> amplitude and frequency) and RJ. I usually take the DCD from the datasheet,
> and put the UBHPJ into RJ and then set PJ in a way that my transmit Eye
> shows the Total Jitter. This isn't 100% correct, but it worked well in the
> past.
>
> BR
> Gert
>
> Von: Hirshtal Itzhak [mailto:ihirshtal@xxxxxxxxxx]
> Gesendet: Dienstag, 25. Juni 2013 12:14
> An: Havermann, Gert; si-list@xxxxxxxxxxxxx
> Betreff: RE: Transmitter Jitter Setup for simulations of 5Gbps SERDES
> Hi again,
>
> Let me try to focus on a certain aspect of my problem:
>
> The sRIO Level II spec details the Tx Jitter values as follows:
>
> Eye Mask = 125mV
>
> Uncorrelated Bounded High Probability Jitter = 0.15UI ptp
>
> Duty Cycle Distortion = 0.05UI ptp
>
> Total Jitter = 0.30UI ptp
>
> The question is: what do these parameters mean?
>
> My understanding: The Transmitter device maximum allowed DCD & jitter.
>
> What the device vendor seems to tell me: The maximum actual DCD & jitter
> present on the Transmitter pins due to both internal jitter generation and
> channel ISI.
>
> So my 1st question is - which is correct?
>
> Then, if the 1st interpretation is true, it seems I need to somehow enter
> all of the above detailed parameters to my simulation transmitter model,
> shouldn't I?
>
> On the other hand, if the 2nd interpretation is true, then it seems I have
> to ask the device vendor to tell me what's the actual jitter generated by
> the device itself, shouldn't I?
>
> Thanks for your help on this matter!
>
> Itzhak Hirshtal
> ----------------------------------------
> Absender ist HARTING Electronics GmbH, Marienwerderstraße 3, D-32339
> Espelkamp; Registergericht: Amtsgericht Bad Oeynhausen; Register-Nr.: HRB
> 8808; Vertretungsberechtige Geschäftsführer: Dipl.-Kfm. Edgar-Peter Düning,
> Dipl.-Ing. Torsten Ratzmann
>
>
> ----------------------------------------
> Absender ist HARTING Electronics GmbH, Marienwerderstraße 3, D-32339
> Espelkamp; Registergericht: Amtsgericht Bad Oeynhausen; Register-Nr.: HRB
> 8808; Vertretungsberechtige Geschäftsführer: Dipl.-Kfm. Edgar-Peter Düning,
> Dipl.-Ing. Torsten Ratzmann
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
> On Behalf Of Havermann, Gert
> Sent: Wednesday, June 19, 2013 3:00 PM
> To: Hirshtal Itzhak; si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] AW: Transmitter Jitter Setup for simulations of 5Gbps
> SERDES
>
> Hi Itzhak,
>
> Quite honestly I don't know hyperlinx in that detail. You should ask the
> support or maybe some helpfiles to find out which type of Jitter has to be
> used.
>
> You could try to add one jitter component at a time and measure the jitter
> in the simulation result to check if the input Jitter equals the output
> Jitter. This way you can find out which parameter to change in which way.
>
> BR
> Gert
>
>
> ----------------------------------------
> Absender ist HARTING Electronics GmbH, Marienwerderstraße 3, D-32339
> Espelkamp; Registergericht: Amtsgericht Bad Oeynhausen; Register-Nr.: HRB
> 8808; Vertretungsberechtige Geschäftsführer: Dipl.-Kfm. Edgar-Peter Düning,
> Dipl.-Ing. Torsten Ratzmann
>
> -----Ursprüngliche Nachricht-----
> Von: Hirshtal Itzhak [mailto:ihirshtal@xxxxxxxxxx]
> Gesendet: Mittwoch, 19. Juni 2013 13:36
> An: Havermann, Gert; si-list@xxxxxxxxxxxxx
> Betreff: RE: Transmitter Jitter Setup for simulations of 5Gbps SERDES
>
> Hi Gert,
>
> I did exactly that!!
> The question was: Am I correct in doing so?
> And what about the non-random jitter? Did I set it up correctly?
>
> Also, I've heard an opinion saying I shouldn't set these jitter values at
> all, but take instead the jitter specification of the Transmitter Reference
> Clock! Is that true?
>
> Regards
> Itzhak
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
> On Behalf Of Havermann, Gert
> Sent: Wednesday, June 19, 2013 12:58 PM
> To: Hirshtal Itzhak; si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] AW: Transmitter Jitter Setup for simulations of 5Gbps
> SERDES
>
> The Jitter Values can be given in either "RMS" or "Peak to Peak". Check
> what kind of input the simulator engine needs, and if it agrees to the
> datasheet numbers you punched in. If simulator uses RMS and Datasheet gives
> P2P, then you need to convert the jitter values using a BER based
> conversion table.
>
> BR
> Gert
>
>
> ----------------------------------------
> Absender ist HARTING Electronics GmbH, Marienwerderstraße 3, D-32339
> Espelkamp; Registergericht: Amtsgericht Bad Oeynhausen; Register-Nr.: HRB
> 8808; Vertretungsberechtige Geschäftsführer: Dipl.-Kfm. Edgar-Peter Düning,
> Dipl.-Ing. Torsten Ratzmann
>
> -----Ursprüngliche Nachricht-----
> Von: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
> Im Auftrag von Hirshtal Itzhak
> Gesendet: Mittwoch, 19. Juni 2013 11:57
> An: si-list@xxxxxxxxxxxxx
> Betreff: [SI-LIST] Transmitter Jitter Setup for simulations of 5Gbps SERDES
>
> Hello all,
> I have a question relating to the proper use of jitter in hi-speed
> simulations of several Gbps pairs.
>
> I've been using HyperLynx IBIS-AMI Channel Analysis tool in order to
> simulate 5Gbps channels going from one PCB to another one through a
> motherboard.
> I use IBIS-AMI models from the Tx/Rx vendors and S-Parameter models for
> the connectors involved.
>
> The main problem for me is understanding how to use the jitter
> specification for the transmitter.
>
> The transmitter data sheet defines miscellaneous Near-End (Tx) Template
> Intervals, part of which are jitter intervals, which include T_UBHPJ
> (Uncorrelated Bounded High Probability Jitter) of 0.15UIptp, T_DCD
> (Duty-Cycle Distortion) of 0.05UIptp and T_TJ (Total Jitter) of 0.30UIptp.
>
> I have been using these parameters as follows inside the simulation tool
> setup:
>
> -          Dual Dirac Jitter: 1st  mean = -0.1UI, 2nd mean = +0.1UI
> (accounting approximately for the sum of the 1st 2 jitter parameters, which
> equals 0.2UI)
> -          Sigma of Random Jitter = 0.01UI, which results from subtracting
> the1st 2 parameters from the total jitter (yielding 0.1UI) and dividing the
> result by 14 (the ratio [for BER of 10**(-12)] between peak-to-peak jitter
> and Sigma. I rounded the final result up a little to get 0.01UI.
>
> So, to conclude: Have I used the simulation tool's jitter setup correctly
> to account for the Tx jitter definitions? Because when I do that, I get a
> closed eye (relative to the Rx eye-mask spec). Without these jitter
> elements the eye is completely open!
>
> Also, what BER ratio should I use for the Sigma definition? Should it be
> according to the desired BER on the receiver?
>
> Thanks for your help
>
> Itzhak Hirshtal
> Elta
> The information contained in this communication is proprietary to Israel
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> Thank you.
>
>
>
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