John, for bypass applications you can think of both the X2Y and IDCs as having multiple smaller loop areas in parallel. But that is throughout the structure of the ASCII sketch I sent, not just the connection to the external circuit. In a bypass application that connection is dominant. Regards, Steve. At 02:58 PM 5/24/2006, Hill, John wrote: >Istvan, > >Yes, I ran the numbers: > >Electrical length of AVX 0508 LICC is = physical length * square >root of Dielectric Constant. >The Dielectric Constant is somewhere above 10K. Let's use 10K. > >The wavelength is 4 time the quarter wavelength = 4 * the Electrical >length = 4 * 1.27 mm * square root of 10K. > >Frequency = C / wavelength = C / 4 * 1.27 mm * square root of 10K = 590 MHz. > >But the resonance on the data sheet is 10 MHz. > >So I guess we are back to the lead inductance and the capacitance of >the MLCC causing the series resonance. > >And this lead inductance can be reduced with a reduction in the loop >area of the leads to the MLCC and by reducing the length of the >leads. I am guessing that is why the IDC and X2Y capacitors work. >They reduce the area of the loop of current feeding the capacitor. >Is this correct? > >Best regards, > >John > > > > >---------- >From: Istvan.Novak@xxxxxxx [mailto:Istvan.Novak@xxxxxxx] >Sent: Wednesday, May 24, 2006 4:49 PM >To: Hill, John >Cc: steve weir; Larry Smith; Mark.Randol@xxxxxxxxxx; si-list >Subject: Re: [SI-LIST] Re: Capacitors arrays. worth it or not? > >John, > >The series resonance frequency of the mounted capacitor does >not directly relate to the open-ended transmission line of >the capacitor body. The vertical transmission line that >Larry referred to has high losses, partly because of the metal >and dielectric losses, but also due to the electrical loading >of the plates. You can get this kind of model described in: >"Slow Wave Causal Model for Multi Layer Ceramic Capacitors" >on ><http://home.att.net/~istvan.novak/papers.html>http://home.att.net/~istvan.novak/papers.html > >Regards, >Istvan > > > >Hill, John wrote: > > >Steve, > >I am not so sure of this. In the MLCC there is a transmission line with >an end that is open. It is the open 1/4 wavelength transmission line >that provides the low impedance on the other side of the part. >Specifically, a 1/4 wavelength away from the open is a short.=20 > >In the IDC part the end is shorted, not open. There is a difference and >I am uncertain how to predict the resonance. That is why Larry's >viewpoint is important. It provided a better understand of the fields in >the parts and why the resonance occurs in the first place. I would like >to understand the IDC parts as well as we now understand the MLCC parts. > >Can anyone explain to me the physics behind the IDC resonance as >compared to the MLCC resonance?=20 > >I would also like to know the Dielectric constant of the MLCC ceramic to >run the numbers and confirm the electrical length of the MLCC part. It >would be interesting to confirm the measured series resonance is truly >predicted by the 1/4 wavelength of the MLCC parts. > >John > >-----Original Message----- >From: steve weir [<mailto:weirsi@xxxxxxxxxx>mailto:weirsi@xxxxxxxxxx]=20 >Sent: Wednesday, May 24, 2006 4:12 PM >To: Hill, John; Larry Smith; ><mailto:Mark.Randol@xxxxxxxxxx>Mark.Randol@xxxxxxxxxx; si-list >Subject: RE: [SI-LIST] Re: Capacitors arrays. worth it or not? > >John, the physics is the same for an IDC. The only difference is=20 >that you multiple coupled lines in each part of Larry's model. Until=20 >you get to really high frequency, you can simply replace those with=20 >smaller equivalent inductance of Ls - Lm. > >Regards, > > >Steve. >At 10:59 AM 5/24/2006, Hill, John wrote: > >> >>Larry, >> >>Your analysis of a capacitor as a transmission line is very insightful. >>It explains the physics behind why a MLCC has a series resonance. I >> > >then > >> >>tried to apply the same technique to an IDC capacitor with both >>terminals of the capacitor on both sides of the part. >> >>I was not able to determine where the first resonance would be. How >>would you apply this technique to an IDC capacitor? And for that matter >>does anyone know where the first resonance would be for an IDC >>capacitor? >> >>Best regards, >> >>John >> >>-----Original Message----- >>From: Larry Smith [<mailto:LSMITH@xxxxxxxxxx>mailto:LSMITH@xxxxxxxxxx] >>Sent: Tuesday, May 23, 2006 12:47 PM >>To: <mailto:weirsi@xxxxxxxxxx>weirsi@xxxxxxxxxx; Hill, John; >><mailto:Mark.Randol@xxxxxxxxxx>Mark.Randol@xxxxxxxxxx; si-list >>Subject: RE: [SI-LIST] Re: Capacitors arrays. worth it or not? >> >>Steve, John - here is another interesting way to look at it. When a >>ceramic capacitor is mounted such that the capacitor plates are >> > >parallel > >> >>to the PCB plates, the capacitor forms a vertical transmission line >> > >with > >> >>inductance per unit length and capacitance per unit length. The far >> > >end > >> >>of the transmission line is open circuit (air) and the near end is >>nearly shorted (PCB power planes present a very low impedance to the >>mounted capacitor). This makes a quarter wavelength resonator similar >>to a 50 Ohm transmission line that is open on one end. At the quarter >>wavelength frequency, the open circuit at the far end becomes a low >>impedance node at the near end. This is the series resonant frequency >>of the capacitor. The peaks and dips that you might see beyond the >>series resonance of the capacitor are associated with the half, 3/4, >>full, 1 1/4, etc, wavelengths of the capacitor transmission line. >> >>To see this effect, you must mount the capacitor on vias and pads that >>have less inductance than the capacitor itself otherwise the resonance >>is completely dominated by the mounting inductance. Tall capacitors >>with very low ESR show this effect the best. I was evaluating a bunch >>of capacitors one time and the 33nF NPO 2220 size capacitor strongly >>exhibited these properties. It is very tall and has low ESR because of >>the many, many plates. I had it mounted on a fixture estimated at 83pH >>but the inductance associated with the capacitor itself was about 1 nH. >>There were perhaps a half a dozen dips and peaks beyond series >> > >resonance > >> >>associated with the transmission line properties of the capacitor. >> >>David Hockanson and I did a couple of papers on this at 2002 and 2003 >>ECTC conference and another one at 2005 Design Con. You can actually >>use the transmission line properties of a capacitor to develop a ladder >>SPICE model and extract the element values. The model accurately >>predicts the reduction of inductance and the increase in ESR of a >>capacitor mounted on low inductance pads. This is important to >> > >simulate > >> >>the parallel resonance that may occur between two capacitors or between >>a capacitor and power planes. Ceramic capacitors have a lot more ESR >>and less ESL than might be expected from a simple RLC model beyond >>series resonance. >> >>Mounting capacitors with the plates perpendicular to the PCB planes >>(rather than parallel) eliminates or at least greatly changes this >>mechanism. As Istvan mentioned, the resonances are very much reduced. >>I believe that there is still an increase in ESR and a reduction of ESL >>beyond series resonance as the current does not want to get very far >>away from the PCB power planes (big inductive loop). Once again, you >>would have to mount the capacitors on very low inductance mounts in >>order to see this. >> >>Regards, >>Larry Smith >>Altera Corporation >> >> >>-----Original Message----- >>From: <mailto:si-list-bounce@xxxxxxxxxxxxx>si-list-bounce@xxxxxxxxxxxxx >> > >[mailto:si-list-bounce@xxxxxxxxxxxxx] > >> >>On Behalf Of steve weir >>Sent: Monday, May 22, 2006 11:27 PM >>To: Hill, John; >><mailto:Mark.Randol@xxxxxxxxxx>Mark.Randol@xxxxxxxxxx; si-list >>Subject: [SI-LIST] Re: Capacitors arrays. worth it or not? >> >>John, you've got it. The vertical orientation makes for N very small >>cavities all acting in parallell. Hence, the secondary resonance >>occurs at a much higher frequency. >> >>Regards, >> >> >>Steve. >>At 01:50 PM 5/22/2006, Hill, John wrote: >> >>> >>>Steve, >>> >>>I'm sorry to be a little thick on this issue, but I may be getting >>> > >the > >>> >>>two orientations confused. If I understand you correctly, the >>> > >following > >>> >>>is true: >>> >>>It is Edie currents that keep the current concentrated in the lower >>>plates of a capacitor when the capacitor is mounted horizontally, >>> > >which > >>> >>>we are defining as having the plates parallel to the board. This >>> >> >>creates >> >>> >>>a resonate cavity under the part. >>> >>>When the capacitor is mounted with the plates perpendicular to the >>> >> >>board >> >>> >>>the current flows through all the plates. >>> >>>Is this correct? >>> >>>John >>> >>> >>> >>> >>>--------------------------------------- >>>The information in this email and attachments hereto may contain >>>legally privileged, proprietary or confidential information that is >>>intended for a particular recipient. If you are not the intended >>>recipient(s), or the employee or agent responsible for delivery of >>>this message to the intended recipient(s), you are hereby notified >>>that any disclosure, copying, distribution, retention or use of the >>>contents of this e-mail information is prohibited and may be >>>unlawful. When addressed to Takata customers or vendors, any >>>information contained in this e-mail is subject to the terms and >>>conditions in the governing contract, if applicable. If you have >>>received this communication in error, please immediately notify us >>>by return e-mail, permanently delete any electronic copies of this >>>communication and destroy any paper copies. >>>--------------------------------------- >>>-----Original Message----- >>> >>>From: steve weir [<mailto:weirsi@xxxxxxxxxx>mailto:weirsi@xxxxxxxxxx] >>>Sent: Monday, May 22, 2006 2:41 PM >>>To: Hill, John; >>><mailto:Mark.Randol@xxxxxxxxxx>Mark.Randol@xxxxxxxxxx; si-list >>>Subject: Re: [SI-LIST] Re: Capacitors arrays. worth it or not? >>> >>>John, when the plates of a cap are parallel to the planes, eddy >>>currents block field penetration to the upper plates through the >>>cavity. The field still goes around the terminal metalization. This >>>makes a resonant cavity. >>> >>>Steve. >>>At 10:50 AM 5/22/2006, Hill, John wrote: >>> >>>> >>>>Mark,=3D20 >>>> >>>>We have uploaded an application note from American Technical >>>> > >Ceramics > >>>> >>>>concerning placing capacitors vertical and horizontal. The URL is: >>>> >>>><http://si-list.org/files/tech_files/ATC%20select_cap_wireless.pdf>http://si-list.org/files/tech_files/ATC%20select_cap_wireless.pdf >>>> >>>>I have also sent an e-mail to the application engineer about the >>>> >> >>issue >> >>>> >>>>of eddy currents limiting the field. The data in the application >>>> > >note > >>>> >>>>does not look like it supports the idea and I do not understand the >>>>physics.=3D20 >>>> >>>>John >>>> >>>> >>>>=3D20 >>>> >>>>--------------------------------------- >>>>The information in this email and attachments hereto may contain >>>> >>> >>>legally =3D >>> >>>> >>>>privileged, proprietary or confidential information that is >>>> > >intended > >>> >>>for =3D >>> >>>> >>>>a particular recipient. If you are not the intended recipient(s), >>>> > >or > >>> >>>the =3D >>> >>>> >>>>employee or agent responsible for delivery of this message to the = >>>> > >=3D > >>>> >>>>intended recipient(s), you are hereby notified that any disclosure, >>>> > >=3D > >>>> >>>>copying, distribution, retention or use of the contents of this >>>> >> >>e-mail >> >>> >>>=3D >>> >>>> >>>>information is prohibited and may be unlawful. When addressed to >>>> >> >>Takata >> >>> >>>=3D >>> >>>> >>>>customers or vendors, any information contained in this e-mail is = >>>> > >=3D > >>>> >>>>subject to the terms and conditions in the governing contract, if = >>>> > >=3D > >>>> >>>>applicable. If you have received this communication in error, >>>> > >please > >> >>=3D >> >>>> >>>>immediately notify us by return e-mail, permanently delete any =3D >>>>electronic copies of this communication and destroy any paper >>>> > >copies. > >>>> >>>>--------------------------------------- >>>>-----Original Message----- >>>> >>>>From: <mailto:si-list-bounce@xxxxxxxxxxxxx>si-list-bounce@xxxxxxxxxxxxx >>>> >>> >>>[mailto:si-list-bounce@xxxxxxxxxxxxx] >>> >>>> >>>>On Behalf Of Mark Randol >>>>Sent: Monday, May 22, 2006 10:33 AM >>>>To: si-list >>>>Subject: [SI-LIST] Re: Capacitors arrays. worth it or not? >>>> >>>> >>>>> >>>>>-----Original Message----- >>>>>From: >>>>><mailto:si-list-bounce@xxxxxxxxxxxxx=3D3D20>si-list-bounce@xxxxxxxxxxxxx=3D3D20 >>>>>[mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Jerry >>>>> > >Martinson > >>>>> >>>>>=3D3D20 >>>>>I've always wondered how discrete cap performance is >>>>> > >affected=3D3D20 > >>>>> >>>>>if the caps plates are parallel with the underlying plane >>>>> > >or=3D3D20 > >>>>> >>>>>if they are perpendicular. I'd think that having them >>>>> > >rolled=3D3D20 > >>>>> >>>>>90 degrees >>>>>(perpendicular) might make them perform better in some=3D3D20 >>>>>regions. I wonder how this would extend to arrays and=3D3D20 >>>>>whether arrays are configured rolled or not. Does anyone=3D3D20 >>>>>know? =3D3D20 >>>>> >>>> >>>>American Technical Ceramics (ATC) used to recommend 'vertical' >>>> >>> >>>placement >>> >>>> >>>>of their porcelain caps for just this reason. I've seen it make >>>> >>> >>>several >>> >>>> >>>>100MHz's of difference in the measured resonance frequency. That >>>> > >was > >>> >>>on >>> >>>> >>>>a relatively thick 2 layer PCB, so on a board with a thinner >>>> >> >>component >> >>>> >>>>to ground layer spacing this could be more significant <guess>. I >>>>didn't find it on their web site, but here is their link. >>>> >>>><http://www.atceramics.com/>http://www.atceramics.com/ >>>> >>>>Now how much of this was due to plate coupling to the substrate, or >>>>reduced effective capacitance and inductance because of current >>>> >>> >>>crowding >>> >>>> >>>>towards the new 'bottom' of all the plates, beats me. It seems to >>>> > >me > >>> >>>in >>> >>>> >>>>the horizontal orientation, the upper plates would have slightly >>>> > >more > >>>> >>>>inductance due to the greater loop area. Which effect dominates, >>>>capacitance or inductance? =3D3D20 >>>> >>>>The problem at the time was fixed, so we didn't investigate >>>> > >further. > >>>> >>>>-- >>>>Mark Randol, RF Evaluation & Application Engineer >>>>Not speaking for my company, etc >>>>------------------------------------------------------------------ >>>>To unsubscribe from si-list: >>>><mailto:si-list-request@xxxxxxxxxxxxx>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>//www.freelists.org/webpage/si-list >>>> >>>>For help: >>>><mailto:si-list-request@xxxxxxxxxxxxx>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>http://si-list.org/wiki/wiki.pl?Si-List_FAQ >>>> >>>>List technical documents are available at: >>>> <http://www.si-list.org>http://www.si-list.org >>>> >>>>List archives are viewable at: =3D20 >>>> >>>><//www.freelists.org/archives/si-list>//www.freelists.org/archives/si-list >>>>or at our remote archives: >>>> >>>><http://groups.yahoo.com/group/si-list/messages>http://groups.yahoo.com/group/si-list/messages >>>>Old (prior to June 6, 2001) list archives are viewable at: >>>> <http://www.qsl.net/wb6tpu>http://www.qsl.net/wb6tpu >>>>------------------------------------------------------------------ >>>>To unsubscribe from si-list: >>>><mailto:si-list-request@xxxxxxxxxxxxx>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>//www.freelists.org/webpage/si-list >>>> >>>>For help: >>>><mailto:si-list-request@xxxxxxxxxxxxx>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>http://si-list.org/wiki/wiki.pl?Si-List_FAQ >>>> >>>>List technical documents are available at: >>>> <http://www.si-list.org>http://www.si-list.org >>>> >>>>List archives are viewable at: >>>> >>>><//www.freelists.org/archives/si-list>//www.freelists.org/archives/si-list >>>>or at our remote archives: >>>> >>>><http://groups.yahoo.com/group/si-list/messages>http://groups.yahoo.com/group/si-list/messages >>>>Old (prior to June 6, 2001) list archives are viewable at: >>>> <http://www.qsl.net/wb6tpu>http://www.qsl.net/wb6tpu >>>> >>>> >> >>------------------------------------------------------------------ >>To unsubscribe from si-list: >><mailto:si-list-request@xxxxxxxxxxxxx>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>//www.freelists.org/webpage/si-list >> >>For help: 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