active filter

An active filter is an electronic circuit that allows certain signals to pass while blocking others, using components like operational amplifiers and resistors or capacitors. Unlike passive filters, which rely only on passive parts such as resistors, capacitors, and inductors, active filters can amplify signals and have greater control over their behavior. They are commonly used in audio systems, radios, and communications equipment to select or eliminate specific frequencies, ensuring the desired signals are transmitted clearly and unwanted noise or interference is reduced. Active filters are versatile, efficient, and essential in modern electronic devices.