[SI-LIST] Re: clock 2nd harmonic
- From: Joel Brown <joel@xxxxxxxxxx>
- To: SI-List <si-list@xxxxxxxxxxxxx>
- Date: Thu, 17 May 2012 12:09:16 -0700
I found this in a paper:
Second Harmonic Emissions
? Currents draw on both edges of the clock
? Clock duty cycle different of 50% (minor factor -10%)
? Crowbar current in clock drivers (small factor)
? Clock driver output has nearly equal capacitance to both Vss and Vdd
(dominant factor)
Not sure what the last one means or what to do about it.
On Thu, May 17, 2012 at 11:43 AM, Joel Brown <joel@xxxxxxxxxx> wrote:
> I am having an EMI problem with the second harmonic of a 65 MHz clock.
> There is a strong emission at 130 MHz.
> What is most likely causing the second harmonic and how can I reduce it?
> The clock waveform does not look seriously distorted.
>
> Thanks
>
>
>
>
--
*Joel Brown**
*
**Chief Electrical Design Engineer
*Z Microsystems, Inc.*
9820 Summers Ridge Rd.
San Diego, CA 92121
Tel: 858-831-7011
Fax: 858-831-7001
joel@xxxxxxxxxx
http://www.zmicro.com
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