Analysis of EMI Reduction Methods of DC-DC Buck Converter

The electromagnetic interference (EMI) generated from the DC-DC buck converter effects the performance of integrated circuits which receive power supply from the buck converter. In this paper, the EMI reduction techniques of DC-DC buck converter are presented. The damping resistor is applied to reduce the output noise of the buck converter. In time domain, this damping resistor technique reduces the output noise of the buck converter significantly but is not effective in reducing high frequency noise components. To resolve this issue, PCB design is modified to contain separate planes for input, output, switching, and ground ports. The TEM-cell, measurement results show that with this modification in addition to the damping resistor, the EMI is significantly reduced over a wide range frequency up to 1GHz.