Ivor, With what you described below there could be problems. These problems woul= d be manifested as noise ripple on your VCC planes which will eat into your= margins budget for Vih and Vil of your devices. By placing only 0.1uf cap= acitors and no other values, you have only minimized your noise on your pow= er planes at about 10mhz. You can never eliminate your parallel resonance but adding additional capac= itors will lower the overall inductance of the mounting capacitors which (w= hen intersected with your plane capacitor) will lower the impedance holes s= omewhat and move them out higher in frequency. But again, they will never = be eliminated. You should use more capacitor values for sure. Dan -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On= Behalf Of Bowden, Ivor Sent: Friday, March 28, 2008 7:24 AM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] PDS analysis? Hi SI Experts, Say you have a typical PCB with modern technology mix of CPU, DSP, DDR, GIG= E, PCIE, etc. Say it is a multi-layer stackup in the form of GND-SIG-SIG-GN= D sets, with the power distribution centered in the stackup as solid ground= plane - split power plane - split power plane - solid ground plane, using = 1oz copper and 3.5 mil dielectric. Assuming the split power planes utilize = sufficient area to keep the point to point inductance and resistance to rea= sonable values, and 0.1uF ceramic bypass caps are evenly placed at device p= ins, and bulk capacitance is placed as needed, would there be reason to exp= ect any problems, such as plane resonance, etc? If so, what would be the ob= servable real world manifestations, in terms of circuit performance and pow= er pins scope waveforms? Would there be significant advantage to analyzing = this PDS, or should following this "industry standard practice" for PCB PDS= be sufficient to expect robust behavior? Thanks, Ivor Bowden Senior Hardware Engineer Curtiss-Wright Controls Embedded Computing 10201 Wateridge Circle Suite 300 San Diego, CA 92121 858-452-0020 x 4405 ibowden@xxxxxxxxxxxxxxxxx _______________________________________________________________________ This e-mail and any files transmitted with it are proprietary and intended = solely for the use of the individual or entity to whom they are addressed. = If you have reason to believe that you have received this e-mail in error, = please notify the sender and destroy this email and any attached files. Ple= ase note that any views or opinions presented in this e-mail are solely tho= se of the author and do not necessarily represent those of the Curtiss-Wrig= ht Corporation or any of its subsidiaries. Documents attached hereto may c= ontain technology subject to government export regulations. Recipient is so= lely responsible for ensuring that any re-export, transfer or disclosure of= this information is in accordance with applicable government export regula= tions. The recipient should check this e-mail and any attachments for the = presence of viruses. Curtiss-Wright Corporation and its subsidiaries accept= no liability for any damage caused by any virus transmitted by this e-mail= . ------------------------------------------------------------------ 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