To reinforce immunities around GHz frequencies by EMI noise suppression filters

With recent advances in telecommunications using GHz range communication technologies, it is necessary to ensure product immunity from high frequency radio waves. Conventionally, shielding and/or feed through capacitors have been used to suppress EMI noise in the GHz range. However, this method has difficulties since a feed through capacitor must be mounted in a metal plate or equivalent. Although surface mount ferrite beads are simple to mount, their performance is limited in the GHz range. Newly developed EMI filters which have improved performance in the GHz range and are able to be mounted without a shielding case are examined. The new EMI filters improve the noise suppression by approximately 20 dB around 1 GHz as compare to conventional EMI filters. Evaluations using actual equipment illustrate the superior performance of the new EMI filters as compared to conventional filters such as surface mount ferrite beads. These new EMI filters are expected to ensure product immunity from radio waves at frequencies greater than 1 GHz.