RE: [SI-LIST] : May 9th Presentation: "Radiation from Edge Effec ts in Printe...

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From: Chris Cheng (chris.cheng@3pardata.com)
Date: Tue May 09 2000 - 15:32:53 PDT


yah, and you kill the clock also.

-----Original Message-----
From: sweir [mailto:weirsp@atdial.net]
Sent: Tuesday, May 09, 2000 11:32 AM
To: si-list@silab.eng.sun.com
Subject: Re: [SI-LIST] : May 9th Presentation: "Radiation from Edge
Effects in Printe...

Didn't that open the circuit at the source and prevent the stub from
radiating?
At 09:08 AM 5/9/00 -0400, you wrote:
> >
> > Chris R.:
> >
> > One exemplary case I recently came across had a series-terminated clock
> line
> > that was immediately submerged to a stripline which went to a connector
on
> > the edge of a PCB. The optional card that would use the connector was
NOT
> > installed. The connector receptacle pin rose above the PCB about 3/16
> inch.
> > This small 3/16-inch stub coupled harmonic energy to the SURFACE of the
> PCB
> > (a ground plane) at the SURFACE resonant frequency of the PCB. Surface
> > currents could be measured all over the surface ground plane (with a
small
> > Fischer Communications probe). NASTY radiation resulted.
> >
> > Simple removal of the series termination resistor at the clock driver
end
> > reduced system radiation over 30 dB.
>-----------------------------------------
>How do you explain this significant reduction in emission levels by
>the simple removal of the series termination resistor?
>-----------------------------------------
>
> > Mike
> >
> > Michael L. Conn
> > Owner/Principal Consultant
> > Mikon Consulting
> >
> > *** Serving Your Needs with Technical Excellence ***
> >
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