My name is Meir and I am DFAE.
One of my customers use the ADM2687 - Signal and Power Isolated RS-485 Transceiver.
They have an emission issue on ~180MHz frequency and 360MHz frequency (the second harmony) and they can't to pass the EMC/EMI sertification.
We suppose that this emission is a result of the oscillator of integrated Isolated power supply that his frequency is 180MHz.
Please see the attached files:
Schematics, PCB Layout, Radiated emissions results.
With the special probe we saw that the emission come from the chip.
Appreciate if you could help us to solve this problem.
Thanks a lot,