Ferrite Beads Demystified

High resolution, high performance converters and radio frequency (RF) systems require good power supply noise filtering and high frequency crosstalk reduction between analog and digital domains. An effective method for filtering high frequency power supply noise and cleanly sharing similar supply rails is the use of ferrite beads. A ferrite bead is a passive device that filters high frequency noise energy over a broad frequency range, where it then becomes resistive and dissipates noise energy in the form of heat. This application note presents and discusses Analog Devices’ products that demonstrate the effects of ferrite beads as output filters. Download the white paper for more information on the synchronous step-down switching regulator (ADP2120), and the dc-to-dc switching regulator with independent positive and negative outputs (ADP5071).