From: Grasso, Charles (Chaz) ([email protected])
Date: Tue Mar 28 2000 - 15:11:55 PST
You might be interested in a project led by NCMS that is the
National Centre for Manufacturing Sciences on Embedded
Details may be found at http://www.ewh.ieee.org/r5/denver/rockymountainemc.
Goto Archives and look at the download available in October and November of
2270 Sth 88th Street
Louisville CO 80027
> From: Hansen, Chris[SMTP:[email protected]]
> Sent: Friday, March 24, 2000 1:25 PM
> To: SI List (E-mail)
> Subject: [SI-LIST] : Parallel Plate Capacitance for Bypass
> According to specifications, X7R type chip capacitors used for power
> subsystem bypass seem to become ineffective above 150 to 200 Mhz. For
> frequencies higher up, you are reliant upon the internal parallel plate
> capacitance. I have two questions.
> 1. Is the calculation for the required capacitance that is needed for the
> parallel plate capacitance the same as that used for a discrete chip
> capacitor bypass network, or is there a conservation of charge situation
> where the real answer is Cpp*dVnoise = Cload*dVchange? (where Cpp =
> parallel plate capacitance, dVnoise = tolerable change in power supply
> voltage, Cload = sum of load capacitance being switched simultaneously,
> dVchange = voltage change through driver output switch).
> 2. If you have a power plane sandwiched between 2 ground planes, does the
> parallel plate capacitance double for a given area?
> Thank you,
> Chris Hansen
> Sr. Design Engineer
> DPT & Adaptec Companies
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