[SI-LIST] Re: Reg. EMI/EMC problem..
- From: Istvan Novak <istvan.novak@xxxxxxx>
- To: chundi srikanth <chundis@xxxxxxxxx>
- Date: Tue, 09 Mar 2010 19:49:28 -0500
Hi Srikanth,
From what you described it sounds that you have a conducted noise problem
originated from the switching converter. You probably want to verify
with a
pickup loop placed close to the converter that the 239kHz peak is in fact a
subharmonic of the nominally 500kHz converter switching. In case the
converter was running when you observed the disappearance of this spurious
sideband after replacing the feed with a bench supply, this rules out
radiated
interference between the DAC/ADC and the converter. In case the converter
was not powered up when you replaced the feed with a bench supply, you
need to repeat the experiment with the converter powered and preferably
delivering about the same nominal current to a dummy load. If it is in
fact
conducted noise, you need to improve the output filtering. When doing
so you
need to be careful not to upset the loop stability of the converter.
Regards,
Istvan Novak
Oracle
chundi srikanth wrote:
> Hi Techies,
> Will it be a problem if we use a switching power supply for RF devices like
> High-speed DAC and ADCs? What are the precautions we need to take if we are
> going to use a switching power supply for some high sped RF devices and how
> to over come them?
>
> Right now we have designed on eboard in which one switching power supply was
> placed near the DAC. And the switching frequency is 500KHz. Now wehen i
> observed the RF DAC in spectrum analyzer iam observing a spur at 239KHz of
> level -60dB. If i remove the inductor in that supply path and given the
> external power to the DAC then the spur is not seen. So can you suggest me
> what might be the problem here. And how to over come this problem.
>
> Thanks & Regards
> Srikanth
>
>
>
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List technical documents are available at:
http://www.si-list.net
List archives are viewable at:
//www.freelists.org/archives/si-list
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
