ADUM5000  radiation emission

Hi ADI team.

My customer use ADUM5000W which has 180MHz ocilator internal.

Now, this product put out 360MHz (double wave of 180MHz)  of radiation emission with a number 10MHz of width.and this radiation emission is serious probrem to ensure the prescribed value of the VCCI classA.

For prevent this problem, my customer is put the external parts consult the Application note.

But, they grope the another way. Please tell me the way to prevent the radiation emission except of the Application note.