Hello Ray DC resistance is a bias resistance to ground (there is a reference in Xilinx application note title: "Power Distribution System (PDS) Design: Using Bypass/Decoupling Capacitors") Actually I am trying to simulate schematic from a paper and my results (impedance profile) are not matching or something similar to what is published. regards Nazish --- On Fri, 5/22/09, Ray Anderson <ray.anderson@xxxxxxxxxx> wrote: > From: Ray Anderson <ray.anderson@xxxxxxxxxx> > Subject: [SI-LIST] Re: spice-impedance profile of pdn > To: "nazish irfan" <irfannazish@xxxxxxxxx>, si-list@xxxxxxxxxxxxx > Cc: "Ray Anderson" <raya@xxxxxxxxxx> > Date: Friday, May 22, 2009, 2:38 PM > > In your step 3, what value of DC resistance are you placing > from the > input of the PDN to GND? And why? > > You DC resistance may be swamping the PDN impedance. > > What doesn't seem to make sense? > > > -Ray Anderson > Xilinx Inc. > > > > -----Original Message----- > > From: si-list-bounce@xxxxxxxxxxxxx > [mailto:si-list-bounce@xxxxxxxxxxxxx] > > On Behalf Of nazish irfan > > Sent: Friday, May 22, 2009 2:28 PM > > To: si-list@xxxxxxxxxxxxx > > Subject: [SI-LIST] Re: spice-impedance profile of pdn > > > > > > Hi All > > > > I am trying to simulate in LT Spice to get > impedance profile of power > > distribution network. > > > > steps I am following are: > > > > 1: make a netlist of all cap, ind and resistors > > > > 2: connecting a 1A AC current source at node 1 (input) > so as to make > V=Z > > > > 3: connecting a dc path resistance from node 1 to > ground > > > > 4: then do AC analysis and use .NET to get Z > (impedance) at node 1 > > > > results I am getting does not seems to make sense > > > > Can anybody suggest me something or do anybody has > done this before > and > > can give me sample netlist to get an idea. > > > > regards > > Nazish > > > > > > > > > > > > > > > ------------------------------------------------------------------ > > 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 > > > > > > > This email and any attachments are intended for the sole > use of the named recipient(s) and contain(s) confidential > information that may be proprietary, privileged or > copyrighted under applicable law. If you are not the > intended recipient, do not read, copy, or forward this email > message or any attachments. Delete this email message and > any attachments immediately. > > > ------------------------------------------------------------------ > 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 > > > ------------------------------------------------------------------ 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