I enjoyed reading all the responses to this posting. The way I would look at it in the time domain is this: During the ramping part of the trapezoid waveform I would think of it as a constant current source, and during the horizontal portion of the trapezoid I would think of it as an open (or constant current source with a 0 A output). In terms of impedance, the AC (small signal) impedance of the constant current source is infinite, the DC impedance is V/I at any given time iteration. Arpad Muranyi Intel Corporation =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] = On Behalf Of group_delay Sent: Tuesday, January 25, 2005 2:11 PM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] capacitor impedance in time domain 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 =3D 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@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: http://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: http://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