Hi, All, I am puzzled about the effect of S21 (Common to Common) of differential mode S-parameter. Assume I have a pair of differential transmission lines, its 3dB BW of S21(Diff to Diff) is 10GHz, and that of S21(Common to Common) is 7GHz. Now the question is what the real 3dB BW the channel is when it transmit differential signal. In my think, when the Common-mode insertion loss is bigger, it does not mean that the S21(Common to Diff) or S21(Diff to Common) will be bigger. So, the common-mode noise should not MUST affect the differential signal. Thank you. Lucian ------------------------------------------------------------------ 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