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

  • From: "Havermann, Gert" <Gert.Havermann@xxxxxxxxxxx>
  • To: "si-list@xxxxxxxxxxxxx" <si-list@xxxxxxxxxxxxx>
  • Date: Tue, 25 Jun 2013 11:01:33 +0000

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
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Thank you.



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Aerospace Industries Ltd. and/or third parties, may contain confidential or 
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addresse thereof. If you are not the intended addressee, please be aware that 
any use, disclosure, distribution and/or copying of this communication is 
strictly prohibited. If you receive this communication in error, please notify 
the sender immediately and delete it from your computer.

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any use, disclosure, distribution and/or copying of this communication is 
strictly prohibited. If you receive this communication in error, please notify 
the sender immediately and delete it from your computer.

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