When an engineer is looking for a ferrite bead for a particular EMI suppression solution, typically the specification of primary interest is the component’s impedance vs. frequency characteristic. Most bead manufacturers will specify this value at the commonly accepted reference frequency of 100MHz, and supplement this “one-point spec" with a typical curve showing the variation of “Z” (impedance) vs. “f” (frequency) for a particular bead in question. With so many characteristics available for so many different applications, it can sometimes be difficult to quickly determine the best choice for a given application. Murata’s offerings can be broadly grouped into five major areas for BLM series, depending on the intended application. The resulting shape of the Z/f curve is determined by both the ferrite formulation and the geometry of the internal electrode structure.