Ralf, Although most of today's CDR shows jitter transfer of 40dB/dec below its corner frequency, the jitter tolerance mask at low frequencies should have 20dB/dec. That is because of previous work in SONET. The corner frequency of the mask is where the low frequency mask intersects with the high frequency mask and is obtained by data_rate/1667. Since you have 0.1UI SJ above the corner frequency, the low frequency mask should be 0.1*(data_rate/1667)/f_sj. Doing the jitter tolerance test, you also may want to keep in mind that the Tx should be running with frequency offset of +/-100ppm so the test is done with the additional phase shift stemmed from asynchronous operation. TK -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Alfred P. Neves Sent: Thursday, March 18, 2010 10:01 AM To: ralf.inova@xxxxxx; si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: Jitter Tolerance Ralf, The composite mix of DJ-RJ, as specified, is intended to test a CDR to insure compliance between platforms, such that a minimum BER is achieved in that system. 10^-12 Bit Error Ratio is a typical number. Adding a dramatic amount of PJ, within the loop bandwidth of the CDR PLL, will result in the PLL losing lock in most cases and does not constitute a interoperability BER type test. Accordingly, it isn't quite clear what your objective is. Are you trying to work around the jitter specification in a BER tolerance type test or are you trying to measure lock range for jitter transfer? Measuring Jitter tolerance is not very easy to do properly, and in the course of our consulting activity, we have unfortunately have seen incorrectly done test methodology of CDR tolerance testing. Alfred P. Neves <*)))))><{ Hillsboro Office: 735 SE 16th Ave. Hillsboro, OR, 97123 (503) 718 7172 Business (503) 679 2429 Mobile Main Corporate office: Teraspeed Consulting Group LLC 121 North River Drive Narragansett, RI 02882 (401) 284-1827 Business (401) 284-1840 Fax http://www.teraspeed.com Teraspeed is the registered service mark of Teraspeed Consulting Group LLC -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of ralf.inova@xxxxxx Sent: Thursday, March 18, 2010 2:21 AM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Jitter Tolerance Dear Experts, I found the following Jitter Tolerance Specification for XAUI: Receiver must be able to tolerate this much jitter DJ : 0.37 UIp-p DJ+RJ : 0.55 UIp-p SJ : additional SJ (on top of DJ+RJ) to limit of mask. -> 8.5 UI < 22.1kHz -> 0.1 UI > 1.875MHz (linear fit between these points) legend: DJ : Deterministic jitter (includes residual ISI, duty-cycle error, etc.) RJ : Random jitter - uncorrelated with any source SJ : Sinusoidal jitter Is there any formula or rule of thump, how much SJ the receiver must tolerate, if one could reduce the DJ and RJ to neglegible values? Thanks in advance, Ralf -- GMX DSL: Internet, Telefon und Entertainment für nur 19,99 EUR/mtl.! http://portal.gmx.net/de/go/dsl02 ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List technical documents are available at: http://www.si-list.net List archives are viewable at: //www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List technical documents are available at: http://www.si-list.net List archives are viewable at: //www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List technical documents are available at: http://www.si-list.net List archives are viewable at: //www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu