[SI-LIST] Re: UltraCAD ESR and Bypass Capacitor Caculator

  • From: "Randol, Mark D" <mark.d.randol@xxxxxxxxx>
  • To: <si-list@xxxxxxxxxxxxx>
  • Date: Tue, 12 Aug 2003 10:06:20 -0700

At high frequencies (for arugument say >500MHz), the via impedance to
the "capacitor planes" limits its usefulness.  For those frequencies, a
close capacitor, appropriately sized, makes lots of difference.

I was working on a 900MHz design at "another company" where putting the
power cap on the leads of the part instead of the PCB made a definite
performance difference.  Of course, that was in a lab environment so we
could do crazy things like that.  ;)

I've also used via inductance for filtering by resonating it with a cap.
It surely wasn't a high quality filter, but it helped. =20

--
Mark Randol, Engineer
Intel Corporation, 5000 W Chandler Blvd, MS CH6-451, Chandler, AZ 85226
480-554-3025 (voice), 480-552-8946 (FAX)
mark.d.randol@xxxxxxxxx


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