Design

Asymmetric filter designs are gaining popularity in industry because of their lower cost and size, however, although this design is successful in eliminating common mode signal issues this paper will show that for certain applications such as TEMPEST these filters offer little to no protection. Symmetric filters, although physically larger and more costly due to the use of more components, provide better filtering in these applications.

Filter connectors are often a misunderstood product for many components engineers. The lack of understanding is often a result of the fact that filter connectors seldom make the “What’s New” headlines and because many engineers typically don’t have a need for them. But those who do are certainly glad they are available!

Every EMI (electromagnetic interference) problem ultimately starts or ends at an electronic circuit. And since electronic components are the building blocks of circuits, it only makes sense to pay attention to the EMI impact of those individual components.

Probably the most important thing to remember about electronic components is that nothing is ideal. Components change values with frequency, current, voltage, and even physical size. And those changes may be nonlinear, adding a new level of complexity. Like a pilot, you need to know the limits so you stay within the envelope of safe performance.

Shielding to control EMI is a staple in modern electronics, playing a major role in military applications. Internal design practices can do much to control EMI in commercial and industrial electronics, but there is a limit to how much you can do. The EMI demands in military electronics are such that good internal design practices are inadequate - shielding is usually needed.