Basically any connection to an opamp can create unwanted susceptibility.
So a small cap to ground preceded by a suitable impedance for the frequencies to be suppressed
will do the job. What pins ?Those that have a substantial length (compared to wavelength) on PCB (or off PCB).
By placing impedance in series with each input/output/supply the effects will already greatly be reduced.
Do not rely on feedback mechanism for this so the 47 pF will do a great job until the max freq of the opamp is exceeded.
Gert Gremmen On 19-2-2020 13:11, John Woodgate wrote:
I see two apparent ways of keeping cellphone noise out of audio op-amps: - 10 pF between + and - inputs; - 47 pF (or similar) from output to inverting input.Which is usually more effective? I suspect that the first one is, but I see it less often.-- Best wishes John Woodgate OOO-Own Opinions Only www.woodjohn.uk Rayleigh, Essex UK - ----------------------------------------------------------------This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <emc-p...@ieee.org <mailto:emc-p...@ieee.org>>All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.htmlAttachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc.Website: http://www.ieee-pses.org/Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe)List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <sdoug...@ieee.org <mailto:sdoug...@ieee.org>> Mike Cantwell <mcantw...@ieee.org <mailto:mcantw...@ieee.org>> For policy questions, send mail to: Jim Bacher <j.bac...@ieee.org <mailto:j.bac...@ieee.org>> David Heald <dhe...@gmail.com <mailto:dhe...@gmail.com>>
-- Independent Expert on CE marking EMC Consultant Electrical Safety Consultant - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <emc-p...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <sdoug...@ieee.org> Mike Cantwell <mcantw...@ieee.org> For policy questions, send mail to: Jim Bacher: <j.bac...@ieee.org> David Heald: <dhe...@gmail.com>
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