Ravindra, A capacitor across Dp and Dn will roll-off the signal. If you know your driver characteristics and how you want to modify the response, the value is a straightforward calculation. Do you mean a cap so small that it will only roll off above 240MHz? I suspect that what you might really be trying to cure is a common mode problem or perhaps mode conversion caused by imbalance in your layout. In that case if you want to use capacitance to cure the problem, the free place to look for it is in the interconnect. You probably don't want to go above 6pF anyway. The trick is staying balanced. If you can't get what you want from manipulating the interconnect, then Johanson Dielectrics goes down to 5.6pF / side in an X2Y which will give you two very well matched caps good out to GHz. Steve. Ravindra Johari wrote: > Hi Guys, > > We are looking to place a differential capacitance of 0402 package between > the two USB differential traces Dp and Dn to improve the signal quality. > Do you have any suggestion as to what is the best possible place to insert > the capacitor pad( near the chip or connector) in the layout and how this can > be done > without any affect to the impedence. > > > Thanks in advance.. > Ravindra > > ------------------------------------------------------------------ > 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 > 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 > > > > -- Steve Weir Teraspeed Consulting Group LLC 121 North River Drive Narragansett, RI 02882 California office (866) 675-4630 Business (707) 780-1951 Fax Main office (401) 284-1827 Business (401) 284-1840 Fax Oregon office (503) 430-1065 Business (503) 430-1285 Fax http://www.teraspeed.com This e-mail contains proprietary and confidential intellectual property of Teraspeed Consulting Group LLC ------------------------------------------------------------------------------------------------------ Teraspeed(R) is the registered service mark of Teraspeed Consulting Group LLC ------------------------------------------------------------------ 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 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