[SI-LIST] Re: Transmitter Jitter Setup for simulations of 5Gbps SERDES
- From: Hirshtal Itzhak <ihirshtal@xxxxxxxxxx>
- To: "'twesterh@xxxxxxxxxx'" <twesterh@xxxxxxxxxx>
- Date: Wed, 26 Jun 2013 12:26:51 +0000
Thanks, Todd
That's exactly what I don't understand. Maybe it's time for me to delve into
the sRIO spec, I just thought someone would have a quick answer for me.
Thanks
Itzhak Hirshtal
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Todd Westerhoff
Sent: Wednesday, June 26, 2013 12:45 PM
To: Hirshtal Itzhak
Cc: conrad.herse@xxxxxxxxxxxxxxxxxx; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Transmitter Jitter Setup for simulations of 5Gbps SERDES
Itzhak,
Jitter placed on the transmitter in an IBIS-AMI simulation directly modulates
the device's output. In other words, if you specify 10ps of P-P jitter on the
TX, that is what you should see at the TX die pad.
I don't remember the details of how jitter is spec'd for sRIO, so I can't
comment there ... but if the jitter is spec'd at a measurement point in the
channel, it stands to reason that the jitter budget for the model would be
somewhat less than what you see at the test point, so that by the time channel
ISI is included, you see the behavior measure for compliance.
Todd.
--
Todd Westerhoff
VP, Software Products
SiSoft
6 Clock Tower Place, Suite 250
Maynard, MA 01754
(978) 461-0449 x24
twesterh@xxxxxxxxxx
www.sisoft.com
"I want to live like that"
-Sidewalk Prophets
On Jun 26, 2013, at 4:08 AM, Hirshtal Itzhak <ihirshtal@xxxxxxxxxx> wrote:
> Hi Conrad,
> The question is: disregarding the specific simulator details, and assuming
> the jitter values are not included in the IBIS-AMI model (as indeed is the
> case with the model I received from the vendor)) should I setup the
> transmitter generated jitter (using simulator facilities) to the sRIO jitter
> numbers, even if the resultant jitter present on the transmitter pins is
> greater (because of channel imperfections etc.)?
>
> In other words, do these parameters represent the (worst-case, maximum
> allowed) "internal" chip mechanisms of jitter generation as would appear on
> its pins if it was loaded with a perfect termination (Actually disregarding
> the "outside world" on the real channel), in which case I should consider it
> as worst-case Tx jitter that I have (or rather my channel design has) to deal
> with?
>
> Thanks
> Itzhak (Hirshtal)
>
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
> Behalf Of Conrad Herse
> Sent: Tuesday, June 25, 2013 4:02 PM
> To: Hirshtal Itzhak
> Cc: 'Gert.Havermann@xxxxxxxxxxx'; si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Re: Transmitter Jitter Setup for simulations of 5Gbps
> SERDES
>
> Hi Hirshtal,
>
> I think the sRIO parameters mean exactly what they state. An sRIO
> compliant transmitter will not exceed (using your numbers here):
>
> 0.30 UI of total jitter
> 0.05 UI of DCD
> 0.15 UI of UBHP jitter
>
> There are other jitter components such as Rj and DDJ which combine with
> the listed DCD and UBHP jitter components, but the total should never
> exceed the 0.30 UI of total jitter (at the sRIO specified BER, can't
> remember if this is 1e-12 or 1e-15 off the top of my head), and the
> listed individual jitter components should never exceed their stated
> values for an sRIO compliant transmitter.
>
> Trying to enter these different jitter components into a simulator for
> stimulation of your channel is simulator dependent, they may need to be
> grouped together and "shoe horned" into categories based on what's
> available in your simulator of choice.
>
> Conrad Herse
> Alcatel-Lucent
>
> On 6/25/2013 7:16 AM, Hirshtal Itzhak wrote:
>> That's OK, but the question remains - what does the sRIO specification
>> really means???
>> -----Original Message-----
>> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
>> Behalf Of Havermann, Gert
>> Sent: Tuesday, June 25, 2013 2:12 PM
>> To: Hirshtal Itzhak; si-list@xxxxxxxxxxxxx
>> Subject: [SI-LIST] AW: Transmitter Jitter Setup for simulations of 5Gbps
>> SERDES
>>
>> Hi Itzhak,
>>
>> what I meant is that the channel creates ISI, and the chip creates ISI, but
>> the chip can not include the Channel ISI.
>> The total Jitter of the transmitter can't include channel ISI.
>> The overall Channel Jitter will include ISI of the Chip and the Channel.
>>
>> BR
>> Gert
>>
>> Von: Hirshtal Itzhak [mailto:ihirshtal@xxxxxxxxxx]
>> Gesendet: Dienstag, 25. Juni 2013 14:06
>> An: Havermann, Gert; si-list@xxxxxxxxxxxxx
>> Betreff: RE: Transmitter Jitter Setup for simulations of 5Gbps SERDES
>>
>> Hi gert,
>>
>> You state that they are both not absolutely correct, but your explanation
>> after that doesn't seem compatible with your statement. The ISI within the
>> chip and package isn't part of the channel ISI!
>>
>> Regards
>> Itzhak
>>
>>
>> ----------------------------------------
>> 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: Tuesday, June 25, 2013 1:02 PM
>> To: si-list@xxxxxxxxxxxxx
>> Subject: [SI-LIST] WG: Transmitter Jitter Setup for simulations of 5Gbps
>> SERDES
>>
>> 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
>>
>> -----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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>>
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