EMI/EMC Suppression in Audio/Video Interfaces
In the past, large external filters and shielded cables were standard ways to address EMI/EMC (electromagnetic interference or electromagnetic compatibility) in audio/video products. These methods added cost, adversely affected performance, and increased the size of the end product. As these products have decreased in size and evolved into the modern audio/video players, the solutions have also had to decrease in size while maintaining or even improving performance. To achieve this, parts like the MAX9511 graphics video interface and MAX9705 Class D audio amplifier have been developed to deliver EMI performance while reducing solution size. This application note shows how this was done, looking at the audio and display interfaces of a typical PC, and at the EMI performance attainable with these devices, in spite of their diminutive size. It investigates the different EMI problems that must be solved for an audio/video interface design and the methods available to do so.