Design of a Low-Power Butterworth Polyphase Filter;

This paper introduces the basic methods for designing the low-pass filter,taking Butterworth filter as an example.

Butterworth-type and Bessel function-type two ways are used for design of Bandpass filter for receiver,and with the help of EDA simulation tools,the bold plot and the group delay characteristics of the filters designed are compared.

The classical method for the digital Butterworth filter design is to work out corresponding analog filter first,then obtain the digital Butterworth filter from the bilinear transform,therefore the traditional method relies on the analog filter,and cannot obtain the zeros-poles plot equal filter.

In order to make the digital filter to maintain the frequency characteristic of the original analog filter,a expression for the prewarping is derived according to the definition of the bilinear transform,and a low-pass Butterworth digital filter is designed.