Active filter

A circuit that cancels out harmonic components of current by switching small passive components (coils) with active components in order to improve power factor. Unlike passive filters—another type of power factor correction circuit—which have disadvantages such as being "bulky," having "narrow input current and voltage ranges," "not being able to achieve power factors above 0.9," and "difficulty in design," this method allows for miniaturization and has become the mainstream power factor correction circuit.