More EMI Mitigation

Wasting energy in transmitting a signal can have other unintended effects. It can affect the quality of the signal itself.


With electromagnetic interference a major design challenge today in any product that sends or receives a signal, determining how to lessen the impact of this phenomenon was addressed to a large extent in my article, “EMI Cuts a Wide Swath,” but there are a few additional techniques that are important to highlight.

Erick Olsen, marketing director at NXP explained that higher performance components could also be used, which do cost money, but are able to improve the quality of the signal.

For example, in a standard radio transmitter, the voice signal is going to get converted on the transmit side digital to analog, then on the receive side there is an analog to digital converter which takes the incoming RF analog energy and converts it to digital.

“By having very high-performance converters you are able to improve the signal-to-noise ratio of the overall system and reduce the effects of EMI coming from and intentional or unintentional source,” Olsen said.

Another way to manage EMI is to improve the transmitter performance in the first place, he said. “If you have a transmitter that is transmitting a lot of energy outside of the intended frequency range, it’s wasting energy and it’s also potentially impacting the receiver for an adjacent system or its own system.”

By having systems that use advanced linearization techniques such as digital pre-distortion, which is used often in base stations today, you not only improve the overall efficiency of the transmitter but you also reduce all the harmonic content, which is wasted energy, and reduce the chance for electromagnetic interference, Olsen concluded.

Further, commercial EMI simulation and analysis tools from companies such as CST, The Mathworks, Mentor Graphics and Ansys provide engineering teams with additional tools to understand and improve their designs before they hit the field.

Interestingly, Ansys, which recently bought Apache, has tools that can accept power and chip models from Apache’s software in its EMI tools.

~Ann Steffora Mutschler

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