Filters are electronic circuits that are used to remove unwanted frequencies or signals from a circuit or system. They are commonly used in a wide range of applications, including audio and video systems, telecommunications, and industrial control systems.
Filters are characterized by their frequency response, which is the way that the filter behaves with respect to different frequencies. Different types of filters have different frequency response curves, and they are designed to pass, reject, or attenuate specific frequency ranges. Some common types of filters include low-pass filters, which pass low frequencies and reject high frequencies; high-pass filters, which pass high frequencies and reject low frequencies; band-pass filters, which pass a range of frequencies within a certain band and reject frequencies outside of the band; and band-stop filters, which reject a range of frequencies within a certain band and pass frequencies outside of the band.
Filters are also used for electromagnetic interference (EMI) suppression. In these applications, the filter acts as a barrier to electromagnetic fields, blocking the transmission of EMI and preventing it from interfering with other electronic circuits. EMI filters are often used in electronic equipment that is sensitive to EMI, such as medical devices and military systems.