Ferrite bead model extraction and its application in high-performance ASIC analog power filtering

High performance ASICs (Application-Specific Integrated Circuits) are getting dominant in modern high-end networking systems. Provisions on the power supplies for these extremely high integrated ASICs are somewhat demanding and strict especially for sensitive analog power rails. To meet the power requirements from ASIC vendors, ferrite bead is used to fulfil the analog filtering. In order to complete the filter design and analysis, a genetic algorithm is developed to extract circuit model from a ferrite bead impedance curve. The extracted circuit model is used for filter performance analysis. As a case study, the designed filter is implemented on a PCB (printed circuit board) in a real product. Measured power noise on the analog power rail confirms that the ferrite bead filter design is successful and the analog power meets the specifications from ASIC vendors.