Electronic – Shall I use a choke or a bead to filter analog power supply

filterinductorpower supply

Often I have a 3.3V or 5V mixed-signal circuit with a microcontroller running in the 10 MHz range and some analog circuitry, e.g. audio or analog sensor signals, powered from a wall-wart style supply or USB.

So a problem I often come across is how to filter the supply for the analog signals. Shall I use a ferrite bead or a choke? More inductance or less? Or just an RC filter?

Best Answer

For filtering large frequencies I'd recommend the ferrite. The parasitic capacitance of inductors makes them essentially useless for filtering high frequencies.