*From*: "Haller, Robert" <rhaller@xxxxxxxxxxxxx>*To*: Istvan Novak <istvan.novak@xxxxxxx>, "Sandhya I. M." <sandhya.im@xxxxxxxxxxxxx>*Date*: Fri, 28 Aug 2009 10:11:03 -0400

Istvan, If you suspected a Plane resonance in a unusual shape, and you wanted to experimentally fix it how would you do that ? For Example, let's say you had a shape similar to an inductive pickup (square loop), and you wanted to experimental eliminate the resonance how could you accomplish that ? If you fixture up a spectrum analyzer to the Plane and excited it, would you expect to see the resonances show up as spurs in the power spectrum at the resonant frequency(s)? Regards Bob Haller Enterasys Networks -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Istvan Novak Sent: Thursday, August 27, 2009 8:26 AM To: Sandhya I. M. Cc: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: Power Plane resonance analysis Hi San, If you have the good luck to have rectangular plane shapes, you can simply calculate the modal resonance peak frequencies from the propagation delay along each of the two sides of the rectangle. 1/(2*tpd) gives you the lowest resonance peak, and you will get all of the harmonics, so it becomes a double infinite series. On typical PCB dimensions today, the first five or ten resonance peaks matter in self impedance; the higher-order modes will tend to blend together into an inductive slope. For more complex shapes the modal resonance frequencies need to be calculated by an appropriate software. You can go from simple and low-cost tools like EZPlane (http://www.ems-plus.com/ezpowerplane.html) to more sophisticated tools like Sphinx (http://www.e-systemdesign.com/products.aspx) to high-end tools such as Ansoft SiWave or HFSS. For HFSS and correlation on power planes, you can check out the Unofficial HFSS User forum (http://www.hfss-forum.com/). To make sure that resonances do not create a problem, best and cheapest defense is to make sure you dont excite them. You can do this by creating a stackup to minimize signal-return currents going through unrelated power-ground cavities. To reduce the resonances themselves, you can either sprinkle the planes with many capacitors, match the planes or use thin laminates, or a combination of these. If you sprinkle the planes in the old-fashioned brute-force manner, you could use the same capacitance value, say 0.1uF or 1uF. Key is minimizing the inductance in the capacitor connections because with the cumulative inductance of all capacitors on the plane you want to stay below a couple of percents of the plane's inductance. You can read more on these design options at http://www.electrical-integrity.com/, go to Paper download. In the Tool download section you can also find simple illustration tools for plane resonances. For measurement options, you can look at the paper "Frequency Domain Power Distribution Measurements - An Overview" from DesignCon 2003 East, Boston, MA, June 23-25, 2003. You will find it at the site above. For more details and tips, you can look at the book Frequency-Domain Characterization of Power Distribution Networks, Artech House, 2007. Regards, Istvan Novak SUN Microsystems Sandhya I. M. wrote: > Hi SI experts, > > If any one can help me in doing PCB Power Plane resonance analysis by > sharing documents or by explaining how it occurs. > > What are the causes of PCB Power Plane resonance analysis > How can we measure resonant frequency > How decoupling caps helps in suppressing resoinance in planes. > What are the factors we should consider while doing resonance analysis. > > Thank you > > Regards > san > > ------------------------------------------------------------------ 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 technical documents are available at: http://www.si-list.net 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 ------------------------------------------------------------------ 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 technical documents are available at: http://www.si-list.net 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

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**[SI-LIST] Re: Power Plane resonance analysis***From:*Istvan Novak

**References**:**[SI-LIST] Power Plane resonance analysis***From:*Sandhya I. M.

**[SI-LIST] Re: Power Plane resonance analysis***From:*Istvan Novak

- » [SI-LIST] Power Plane resonance analysis - Sandhya I. M.
- » [SI-LIST] Re: Power Plane resonance analysis - Istvan Novak
- » [SI-LIST] Re: Power Plane resonance analysis - Aleksandr Oysgelt
- » [SI-LIST] Re: Power Plane resonance analysis - steve weir
- » [SI-LIST] Re: Power Plane resonance analysis - Ihsan Erdin
- » [SI-LIST] Re: Power Plane resonance analysis - Ihsan Erdin
- » [SI-LIST] Re: Power Plane resonance analysis - Haller, Robert
- » [SI-LIST] Re: Power Plane resonance analysis - Istvan Novak
- » [SI-LIST] Re: Power Plane resonance analysis - colin_warwick