Electromagnetic Interference (EMI) and Electromagnetic Compatibility (EMC) are crucial considerations in the design of electronic circuits, including buck converters. Here are some key considerations and techniques to address EMI and EMC issues in a buck converter design:

Filtering Components: Place input and output filters to suppress high-frequency noise. Common-mode and differential-mode filters can be used to attenuate conducted noise. Use capacitors and inductors strategically to filter out high-frequency components. Ferrite beads can also be effective in reducing high-frequency noise.

Grounding and Layout: Pay careful attention to the layout of the PCB (Printed Circuit Board). Proper grounding techniques are crucial to prevent ground loops and to minimize the loop area of the current paths. Keep high-current loops as small as possible to reduce the loop area and consequently minimize radiated emissions.

Shielding: Use shielding techniques, such as placing critical components in metal enclosures or using shielding materials, to contain electromagnetic radiation. Shield sensitive components from each other to prevent cross-talk and interference.

Component Placement: Position critical components away from each other to reduce the chance of coupling. This includes separating the input and output sections of the converter. Keep sensitive components, such as analog and digital sections, separated and properly shielded.

Ground Plane: Implement a solid ground plane to provide a low-impedance return path for currents, reducing the likelihood of ground loops and minimizing radiation.

Snubber Networks: Use snubber networks across the switch (diode) to dampen voltage spikes and ringing. This can help reduce radiated emissions and improve EMC performance.

Component Selection: Choose components with low EMI characteristics. For example, opt for low ESR (Equivalent Series Resistance) capacitors and fast-recovery diodes. Consider using components with integrated EMI reduction features.

Frequency and Synchronization: Adjust the switching frequency to avoid critical resonances with other components in the system, minimizing the likelihood of electromagnetic interference. Synchronize the switching frequency with other converters in the system if possible.

Compliance with Standards: Ensure that the buck converter design complies with relevant EMC standards and regulations applicable to your region or industry.

Testing and Validation: Conduct thorough testing of the buck converter under various operating conditions to verify its EMC performance. Use EMC test equipment to measure emissions and susceptibility, making adjustments as needed.

By carefully considering these factors and incorporating appropriate design techniques, you can minimize EMI and enhance EMC in a buck converter design. It's important to note that the specific requirements may vary depending on the application and regulatory standards.