Sourcing the Right EMC Product
Essentially there are two EMC issues to deal with: emission and susceptibility. EMC emission is the generation (source) and EMC susceptibility is the reception (victim) of electromagnetic interference / electromagnetic noise. Electromagnetic noise is created by rapid voltage or current changes and it resonates throughout the host electronic equipment and can spread to other equipment via various interconnect points.
Emission levels vary from application to application, and so too, the EMC products that are available to meet the regulatory guidelines for end products and targeted vertical markets.
Ferrites: The lowest level electromagnetic filtering, Ferrite Beads dissipate unwanted EMI noise through radiated heat and are a great choice for applications that are under 5db of noise on AC line cords and board level filtering in: consumer, hand held, and ultraportable markets.
Surface Mount EMI/RFI Filters: For higher speed applications or more than 5 db of rejection. More common applications are: security equipment, instrumentation, test and measurement equipment as well as PCs and various computer peripheral devices.
Feed through Filters: For higher levels of circuit noise particularly in MIL or harsh industrial environments Feed Through or Bulkhead Filters provide the highest level solution for EMI problems for alternative energy, communications in addition to commercial and military avionics applications.
Inductors: Two key performance criteria for inductors are current handling capability and inductance. RF Inductors are best suited for applications involving high frequency and high ‘Q’ factors requirements such as: mobile communication, satellite receivers, low noise amplification and impedance matching.
Small Signal Inductors: Examples using small signal inductors for low transmission loads are: PC laptops, audio devices, and set-top-boxes.
High Current/High Power Inductors: AC/DC power supplies, DC/DC converters are two primary applications that are driving the high power/high current inductor market.
Radio Frequency (RF) filtering is equally important and has a similar set of components to ensure compliancy to the appropriate regulatory agencies. There are three basic technologies of RF filters: Multilayer filter, Dielectric Filter and SAW filters. These RF Filters can be designed to either allow a specific radio frequency band to pass into a device (bandpass) or keep unwanted ranges of RF signal out of a device (band elimination). Multilayer filters are the most cost effective and provide average levels of RF rejection. Dielectric filters provide good rejection of unwanted RF signals and have the highest power handling capability while SAW filters provide superior levels of RF rejection and are significantly smaller and offer a very low profile for low board height requirements.
EMC component availability has historically been affected by the release of new consumer product platforms, hand held and ultra portable devices as well as seasonal or holiday cycles. Working with a distributor with a broad and deep inventory, like TTI, is key to a procurement strategy that is both robust to secure existing requirements, and nimble to source the leading edge EMC components that drive the enhanced performance required to compete for new product sales is imperative.