Re: [SI-LIST] : No buried/embedded capacitance?

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From: John Kennedy (john.kennedy@cppus.com)
Date: Mon Sep 25 2000 - 08:34:36 PDT


Bob,

many thanks for the reply to which I have two questions:

> Not really. It's the total length of the current loop, not just the body
> inductance of the capacitor alone. A 25 mil deep via hole at each end of the
> capacitor alone will roughly double the 0.6 nH 'specified' body inductance.
> That does not include the pads and traces to get from the capacitor to the vias.

1) In communication with AVX I am told that the inductance for their IDC
(InterDigitated capacitor)devices have a total inductance of 110 pH
which includes via-in-pad connection. If I also use this methodology can
I not expect this value (or close to it)?

> For decoupling an IC lead the usual killer is the lead and bond wire inductance
> back to the chip. Usually several nH.

2) You have got me concerned. Why don't the equations in The Handook of
Black Magic or Micron's Bypass Capacitor Selection note TN-00-06 concern
themselves with the inductance of the IC leads that are being decoupled?

John

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