In the use of modern technology designed filter, Butterworth filter is the most famous of the filter. It has the smooth frequency response, and relatively simple design, performance has not been obvious shortcomings, so it has widely used. because the Q which constitute the filter’s components is less demanding,so it’s more easily produced to meet the design and performance.
This article introduces the concept, role and classification of filter. The current commonly used on filters, its principles for analysis. This article focues on descriping the design process of Butterworth filter ,then simulation with matlab and EWB.