Hi Steve and others, I am actually trying to do some theoretical analysis and for that I am using ideal transmission line and ideal capacitor. In other words, no parasitics. It is a single pulse with zero initial conditions on the capacitor. So in this case Z = 1/jwC, but the question is how to pick w? Thanks, Chris --- In si-list@xxxxxxxxxxxxxxx, steve weir <weirsp@xxxx> wrote: > No, the sine wave impedance is only Z = 1/jwC near DC where you probably > don't care. For moderate frequencies, and assuming that you want to look > right at the capacitor, then the R-L-C model is adequate. But, depending > on the type of dielectric, C may vary considerably across the waveform > amplitude. If you are just trying to pass a pulse, you can get around that > by making C large enough that variations are insignificant to the series > impedance. However, if you are building an equalizer, then the choosing a > suitable dielectric type like plastic that doesn't change Er noticeably > with bias voltage is probably an important choice. > > Then there is the little problem of the initial condition. Is this a > single pulse with the system starting at zero, or is it a pulse in the > midst of a train of pulses? Given your chosen moniker, hopefully you have > the initial conditions in mind. > > Steve > > At 10:11 PM 1/25/2005 +0000, group_delay wrote: > > >Hello, > > > >I am trying to see what kind of an impedance a capacitor will present > >to a trapezoidal signal (finite rise time square wave). For a sine > >wave, we all know it is Z = 1/jwC. I need to know this because, I want > >to find the reflected (from load) waveform magnitude in the following > >situation: > > > >source --> 50 ohm termintion--transmission line--capacitor shorted to > >GND. > > > >Thanks. > > > > > > > >------------------------------------------------------------------ > >To unsubscribe from si-list: > >si-list-request@xxxx 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@xxxx 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 > > > > > ------------------------------------------------------------------ > To unsubscribe from si-list: > si-list-request@xxxx 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@xxxx 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 ------------------------------------------------------------------ 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