Re: Power/ground connections/bypassing on ICs

Larry Smith ([email protected])
Mon, 28 Apr 1997 12:31:14 -0700


Some of us out here really do methodically design decoupling caps into
the product. The methodology was developed and published by:

Larry D Smith,
Decoupling Capacitor Calculations for CMOS Circuits,
Electrical Performance of Electrical Packages Conference,
Monterey CA, Nov 1994,
Pages 101-105.

Since the methodology was published, it has been used it on several
products. Lab measurements with a spectrum analyzer indicate greatly
reduced power supply noise at many frequencies. Also, EMC/EMI radiation
has been measured as much as 10 dB down after using the methodology.
BTW, that guy from IBM works for Sun now... :)

Larry D Smith
Sun Microsystems

> From [email protected] Mon Apr 28 11:06:16 1997
> Date: Mon, 28 Apr 1997 12:05:12 -0600
> From: [email protected] (Gary Peterson)
> To: [email protected]
> Subject: Re: Power/ground connections/bypassing on ICs
> I can't remain quiet on this issue any longer.
> We all know about minimizing and reducing, etc. But does anyone out there
> actually DESIGN their bypassing networks? I sure don't know how to do it!
> If I did, perhaps I could design a bypass network that would serve my needs
> AND the needs of the assembly/manufacturing folks. A few years back, at a
> SPICE class in San Jose, I heard a fellow from IBM state that he designed his
> bypassing networks in the frequency domain. Anyone else doing this?
> I've tried, but without satisfactory results. Any suggestions on scaling
> the problem? Any ideas on how to model the timing jitter between parts
> that are simultaneously switching with ~2ns edges? Are there any bypass network
> designers out there? I'm sure I (at least) could use some real design help on
> this one. No opinions, intuitions or hand-waving please. I have plenty of my
> own and they are probably more conservative than need be.
> Gary P.