EMI Filter Design, 3rd Edition

7Typical EMI Filters—Pros and Cons

Many different types of EMI filter structures are used today. These are primarily the π, T, and L, with Cauer and RC shunts. They include double and triple filters and sometimes even quadruple uses of the mentioned types of filters. Each EMI filter has some positive and negative attributes. Each filter type lends well in certain applications, and in others the filter may not perform as well as required. This chapter presents the various filter types and discusses them in terms of structure, performance, and their individual merits. In addition, the transformer—if used as part of a filter structure—will add to the filter loss. This is discussed in chapter 11.

7.1 The π Filter

We start with a discussion of the ...