Re: adding ceramics across power pins



On Jul 25, 6:32 pm, "Jon Slaughter" <Jon_Slaugh...@xxxxxxxxxxx> wrote:
Why does one have to add ceramic's across power pins along with larger caps
such as tantalum. e.g., 1uF tant an 0.1uF cer?

In theory they just add to 1.1uF and it shouldn't make any difference. It
seems that one should then also add 0.001uF and so on?

In my - moderately humble - opinion, it's all about self-resonant
frequencies. Tantalum's have quite high equivalent series resistances
(ESR), and are perfectly useless at high frequencies, but the ESR is
high enough to damp the much sharper self-resonance of a 100nF ceramic
disk.

http://www.kemet.com/kemet/web/homepage/kfbk3.nsf/vaFeedbackFAQ/53D5333B4453253585256BCD004EBC04/$file/TechTopics%20Vol4No5%20Sep94.PDF

A 10nF "microswave" capacitor can look like a capacitor up to even
higher frequencies.

--
Bill Sloman, Nijmegen

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