Patent ID: 8878456

Claim:
A filter device for filtering high-frequency interference, comprising: a current path between an input and an output; an inductor provided as the first component in the current path and connected to the input; an inverse-polarity protection diode connected in series with and downstream of the inductor; and a voltage buffer and bypass capacitor connected in series with and downstream of the inductor and the inverse-polarity protection diode, the voltage buffer and bypass capacitor having a equivalent series resistance above 200 mΩ; a first filter capacitor provided in a first branch path connected to the current path at a point between the input and the inductor; and a second filter capacitor provided in a second branch path connected to the current path at a point between the inductor and the output; wherein each of the first and second filter capacitors provide a substantially smaller capacitance than the voltage buffer and bypass capacitor.