Refer to http://bwrc.eecs.berkeley.edu/classes/EE290C_S04/ I feel the third reason will have the most possibilities .because PLL is more sensitive to low frequency noise . which is always the main part of the noise of the supply . Regards zheng qi ************************************ qzheng@xxxxxxxxxxxxxxxx <qzheng.hb@xxxxxxxxx > 2006-4-5 ************************************ 2006/4/5, Wei Zhou <wzhou@xxxxxxxxxxx>: > > Zhangkun, > > A typical serial link like PCIE, GE have a PLL on the TX side and a clock= data recovery circuit (CDR) on the RX side. The TX PLL multiply the refere= nce clock up and latch data out. In a lot serial links, data is 8B/10B enco= ded to ensure enough transition edges for the CDR to recover the clock. In = that sense, the clock is "embedded". > > The CDR on the RX side will try to figure out the right timing to sample = data based on the data transition it was seeing. The CDR fundamentally is a= nother PLL, the loop inside the CDR move the sampling edge back and forth t= o have it centered around the center of the data eye, thus recovering or "d= e-embeding" the clock and use the recovered clock to latch in data. > > Wei > > -----Original Message----- > From: si-list-bounce@xxxxxxxxxxxxx on behalf of Zhangkun > Sent: Tue 4/4/2006 8:51 PM > To: si-list > Subject: [SI-LIST] How to embedded and to deembedded the clock to serial = signal, such as GE and PCI-E > > Dear all > Recently, in our product, there is some problem in our product. The seria= l signal, such as GE and PCI-E, has error bits. We have found out the reaso= n: > 1.The serial signal has crosstalk. > 2.The clock signal to PLL has crosstalk. > 3.The analog power of the PLL or the serial signal driver has large po= wer noise. > > I guess the basic reason is that the jitter of clock. Could anybody expla= in to me how the clock signal is embedded to and deembedded from the serial= signal? > > Best Regards > > Zhangkun > 2006.4.5 ------------------------------------------------------------------ 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 FAQ wiki page is located at: http://si-list.org/wiki/wiki.pl?Si-List_FAQ List technical documents are available at: http://www.si-list.org List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu