# [SI-LIST] Re: How is the jitter spec and BER number related to each other

• From: "Rose, Michael" <mrose@xxxxxxxxxxxxxxxxx>
• Date: Wed, 10 Nov 2010 11:49:07 -0500

```Also, checkout Mike Li's excellent paper:
http://www.altera.com/literature/cp/cp-01049-jitter-si-verification.pdf

-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Sent: Wednesday, November 10, 2010 10:28 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: How is the jitter spec and BER number related to each
other

Julia,

Maxim and Agilent have some good papers on jitter, Tektronix has a good
webinar series on jitter. I also suggest you look up information on the
"dual-Dirac Model".

Alcatel-Lucent

> Samit Ashdhir wrote:
>> Hi Julia,
>>
>> A BER bathtub curve provides the relationship between the jitter spec
>> and BER. The curve is the plot of BER vs. sample time from the left
>> edge to the right edge of a data eye. This plot resembles a “bathtub”
>> and is also referred to as a “BERT scan.”
>>
>> BER measurements is across the regions where data transitions occur
>> (the left and right eye edges) and provide the necessary information
>> to calculate TJ. TJ is quantified by noting the points where the BER
>> reduces to 1E-12 (or required limit) at both eye edges. Subtracting
>> that interval from the bit period provides TJ. For example, if the
>> data rate is 1.25 Gb/s, the corresponding bit period is 800 ps. If a
>> BER of 1E-12 occurs at 20 ps and 780 ps, then the total jitter is 800
>> – (780 – 20), or 40 ps.
>>
>> Agilent has some good papers explaining these more.
>>
>> -samit
>>
>> On Nov 9, 2010, at 5:08 PM, "Julia (Zhuyuan) Liu" <zliu@xxxxxxxxxx>
>> wrote:
>>
>>> Hi, Everyone
>>> XLAUI/ CAUI spec specifies the jitter tolerance in UI, assuming the
>>> BER is 1e-12 or 1e-15. Does anyone know how to calculate the jitter
>>> tolerance when the BER is given?
>>>
>>> For example, CAUI has the following note in the spec.
>>> NOTE-A transmitter capable of operating at TJ = 0.3 UI and DJ = 0.16
>>> UI and receiver capable of operating at stress
>>> jitter tolerance of TJ = 0.64 UI and DJ= 0.41 UI would have
>>> sufficient margin for operation at approximately BER 10-15.
>>>
>>>
>>> Thanks,
>>> Julia
>>>
>>>
>>>
>>>
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