[Help]Product fails in Radiated Susceptibility test.

[Nicholas]

During RF Immunity (IEC 61000-4-3) test. The OP AMP inside my product just output a low frequency signal every 3 seconds upon each step starts. Anybody help??? Thanks!!!!!

 

[ada_el]

You don't tell anything about cables, most important things in radiated susceptibility. Try separate them apart one another, try twisting or better shielding them, try to add a filter to the power supply cable.

I hope this can help you.
Ada

 

[artem]

From my experience it is better to :
- use differential input to your amplifier
- use emi filter common mode chokes and ferrite bead to filter signal from input (should be placed as close as possible to input cable entry to pcb)
- use minimum trace width on pcb for your analog parts
- extensive use of ground plane
- filter power supply coming to your analog part
- use better opamp with higher cmrr (for dfferential input scheme)
- use smd components with low physical height
- pay attention also to that opamp output is not exposed to em field as well .

Perhaps shielding is also possible but it has to be justified.

 

[som_raparty]

hi as u said u r opamp is mis behaving
u can try making its gnd strong to earth
and u can also try placing some metal strip (or some ferrite strips available)
near to ic connecting to gnd, if this improves u r problem u can think something in that way to suppress the noise
if can check the pcb design of Iphone they have a metal strip sheilds all around the ic's, this helps in most cases

if u still have the same problem try to figure out the ic properties

thnx
som