Butterworth, Chebyshev, Bessel and Elliptic filters are some of the most widely used practical filters to approximate the ideal response. An active filter is a type of analog circuit that implements an electronic filter that utilizes active components, usually an amplifier. Amplifiers included in a filter design can be used to improve the cost, performance, and predictability of a filter. An active filter uses operational amplifiers together with various electronic components such as resistors and capacitors for filtering. Therefore, the summing amplifier produces an output, which is the amplified version of the sum of the outputs of the active low-pass filter and the active high-pass filter.
If an active filter rejects (blocks) a particular frequency band, it is called an active band stop filter. As time progresses and the study of filters increases, active filters have been the subject of debate. With the connection of the passive filters, the series active power filter functions as a harmonic isolator. If an active filter allows (passes) only low-frequency components and rejects (blocks) all other high-frequency components, it is called an active low-pass filter. If an active filter allows (passes) only one frequency band, then it is called an active bandpass filter.
This means that both the active high-pass filter and the active low-pass filter are cascaded to obtain the output such that it contains only a particular frequency band. If an active filter allows (passes) only high-frequency components and rejects (blocks) all other low-frequency components, then it is called an active high-pass filter.Latest generation active filter with low voltage inverter (left) and active filter with medium voltage SiC inverter (right). In general, the active filter using resistors, capacitors and operational amplifiers has several advantages over passive filters. Active filters are a group of electronic filters that use active components such as an amplifier for their operation.
Therefore, the output of the above block diagram will be the output of an active bandstop, when we choose to have the cut-off frequency of the low-pass filter lower than the cut-off frequency of a high-pass filter. Passive filters connected between the non-linear load and the active power filter in series play an important role in compensating load current harmonics. Active filters offer several advantages over passive filters. They are more cost effective since they require fewer components to achieve a desired result. They also provide better performance since they can be designed to have higher gain and better linearity than passive filters. Additionally, they are more predictable since their performance can be accurately modeled using mathematical equations.
Overall, active filters are a powerful tool for designing electronic circuits that require filtering capabilities. They offer improved cost effectiveness, performance, and predictability compared to passive filters. As technology advances, more sophisticated designs are being developed to further improve their capabilities.