PCB layout modification to change the noise transfer path

To meet EN55015 regulation, the magnetic field distribution of 20W LED driver was tested by near field probes and spectrum analyzer. According to the tested magnetic strength, the interference sources and transfer paths on the PCB board were identified. Because the interference source cannot be changed, the PCB modification scheme was proposed to change the transfer path for the interference suppression. With the updated PCB layout, the conductive emission test result was dramatically improved to meet EN55015 regulation limit.