All, Please note that the correct link is: http://www=2Espeedingedge=2Ecom/ (Th= ere is a typo error in the URL provided by Lee)=2E Elya Original Message: ----------------- From: Lee Ritchey leeritchey@earthlink=2Enet Date: Tue, 30 Dec 2003 10:06:45 -0800 To: si-list@enclustra=2Ecom, si-list@freelists=2Eorg Subject: [SI-LIST] Re: Bypass Capacitor Selection Martin, You have two questions in your message=2E First, package size and second capacitor value=2E Package size first: The motivation for small package size is lowest possible parasitic inductance=2E One must include mounting inductance as part of this=2E When this is added, the difference between the total inductance of an 0402 and 0603 is so small that 0603 is a better choice, a= s it makes assembly easier=2E Capacitor value: Usually, the objective is to achieve a low impedance across a very broad range of frequencies=2E Using a single value capacito= r will not achieve this=2E There are several papers that address this and g= ive insight into how to determine the values and quantities of capacitors=2E = If you send me a separate e mail I can supply some of them=2E One of them is= on my web site www=2Espeedingdge=2Ecom=2E Lee > [Original Message] > From: SI List <si-list@enclustra=2Ecom> > To: <si-list@freelists=2Eorg> > Date: 12/30/2003 5:23:45 AM > Subject: [SI-LIST] Bypass Capacitor Selection > > Dear All, > > After studying many books, the bottom line for high frequency bypass > capacitor selection seems to be the following: > > Use the smallest possible package and then take the largest valued > capacitor available in that package=2E > > Although 0201 capacitors are available, they are kind of hard to > assemble=2E So in our design, we are thinking of using 0402 X5R parts=2E= > > In a 0402 package, the largest value available seems to be 1 uF=2E > > My frequency range of interest is DC to 500 MHz=2E In addition to the > bypass capacitors, I know that there must be a pair of closely spaced > VCC/GND reference planes=2E > > My questions: > 1=2E Does it make sense to only use 1 uF 0402 capacitors for bypassing? > Other people often use a combination of 1 nF/10nF/100nF=2E 2=2E I have b= een > looking at the frequency characteristic of 100 nF 0402 X5R capacitors > given in the data sheets of different manufacturers=2E The impedance vs=2E= > frequency plot often looks quite different from manufacturer to > manufacturer=2E Should I choose the manufacturer with the best frequency= > characteristic or are all such parts almost equivalent? 3=2E Does it mak= e > sense to use surface mount capacitor arrays for bypassing? > > Thanks for all your expert feedback=2E > > Best regards, > Martin Heimlicher, heimlicher__at__enclustra//dot//com > > ------------------------------------------------------------------ > To unsubscribe from si-list: > si-list-request@freelists=2Eorg with 'unsubscribe' in the Subject field > > or to administer your membership from a web page, go to: > http://www=2Efreelists=2Eorg/webpage/si-list > > For help: > si-list-request@freelists=2Eorg with 'help' in the Subject field > > List technical documents are available at: > http://www=2Esi-list=2Eorg > > List archives are viewable at: =20 > =09=09http://www=2Efreelists=2Eorg/archives/si-list > or at our remote archives: > =09=09http://groups=2Eyahoo=2Ecom/group/si-list/messages > Old (prior to June 6, 2001) list archives are viewable at: > =09=09http://www=2Eqsl=2Enet/wb6tpu > =20 ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@freelists=2Eorg with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: http://www=2Efreelists=2Eorg/webpage/si-list For help: si-list-request@freelists=2Eorg with 'help' in the Subject field List technical documents are available at: http://www=2Esi-list=2Eorg List archives are viewable at: =20 =09=09http://www=2Efreelists=2Eorg/archives/si-list or at our remote archives: =09=09http://groups=2Eyahoo=2Ecom/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: =09=09http://www=2Eqsl=2Enet/wb6tpu =20 -------------------------------------------------------------------- mail2web - Check your email from the web at http://mail2web=2Ecom/ =2E ------------------------------------------------------------------ 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.org 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