A bandpass filter is characterized by its frequency characteristics shown in Fig. 1. Like its low-pass counterpart, a bandpass filter can be implemented using either only LC (passive) components or RC plus active components. The latter choice eliminates the need for inductors and results in what is called an active filter. The wide-band filter of Fig.1 can be designed to exhibit anyone of the low-pass filter characteristics, e.g., the Butterworth, Chebyshev or the Bessel characteristics.