Yes, overly small coupling cap can cause droop on the DC component contained in the signal. Also, when the impd. of the coupling cap is large enough, ISI will be generated due to both bandwidth limitation and reflection caused by the cap. -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of I Ilamparidhi Sent: Thursday, November 13, 2014 11:25 AM To: balaseven@xxxxxxxxx Cc: Venkat Pappu; si-list@xxxxxxxxxxxxx; Chris.Cotton@xxxxxxxxxxx Subject: [SI-LIST] Re: Double-AC coupling Hi, Apart from discontinuity issues, having two ac-cap may also cause “DC wandering” But the performance degradation highly depends on the data pattern i.e. more precisely the amount of energy below the corner frequency. Generally the impact is very negligible on highly dc-balanced data like 8b/10b encoded. Ilam On Wed, Nov 12, 2014 at 11:39 AM, bala <balaseven@xxxxxxxxx> wrote: > Hi All, > What will happen if my serdes clock has two ac coupling capacitor.Does > this increase low frequency jitter? > > Regards > bala > On 12 Nov 2014 02:45, "Venkat Pappu" <ppreshu@xxxxxxxxx> wrote: > > > Depends on the Impedance of the cap at the data rate. > > Location of the cap, it will be better if it is closer to the receiver. > > > > -Prashant > > > > On Tue, Nov 11, 2014 at 8:02 AM, Cotton, Chris > > <Chris.Cotton@xxxxxxxxxxx > > > > wrote: > > > >> You don't mention data rate but generally a link that runs > >> successfully with internal AC coupling will also run with > >> additional external AC coupling albeit with reduced margins. The > >> amount of reduced margin will depend on how much of a discontinuity > >> the external AC capacitors > (including > >> any additional vias or etch that me required to get the AC cap) > presents. > >> > >> Chris > >> > >> -----Original Message----- > >> From: si-list-bounce@xxxxxxxxxxxxx > >> [mailto:si-list-bounce@xxxxxxxxxxxxx > ] > >> On Behalf Of bala > >> Sent: Tuesday, November 11, 2014 2:02 AM > >> To: si-list@xxxxxxxxxxxxx > >> Subject: [SI-LIST] Double-AC coupling > >> > >> Hi, > >> What will happen if a link has two set of AC coupling(internal as > >> well > as > >> external). > >> > >> I know this will reduce the total effective capacitance, does this > >> contribute to Link error? > >> > >> -- > >> bala > >> > >> > >> ------------------------------------------------------------------ > >> 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 forum is accessible at: > >> http://tech.groups.yahoo.com/group/si-list > >> > >> 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 forum is accessible at: > >> http://tech.groups.yahoo.com/group/si-list > >> > >> 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 forum is accessible at: > http://tech.groups.yahoo.com/group/si-list > > 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 > > > -- Regards, Ilam Mobile No : +65 86982621 " Any action that results in pain to self or others at present or in the future, through body or mind - that is sinful action! " ------------------------------------------------------------------ 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 forum is accessible at: http://tech.groups.yahoo.com/group/si-list 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 forum is accessible at: http://tech.groups.yahoo.com/group/si-list 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