滤波器特性的非等波纹逼近方法

本文提出滤波器特性的非等波纹逼近方法。利用切比雪夫多项式构成有理函数，并与频率相关的系数组成特征函数，从而获得接近于同阶数椭圆函数滤波器的衰减特性，明显优于切比雪夫和逆切雪夫滤波器。理论明晰，过程简单，便于计算机编程。非等波纹逼近方法是最平坦逼近和等波纹逼近的一种中间形式，有其实用价值。

The Technique of Non-Equiripple Approximation for Filter Characteristics

The technique of non-equiripple approximation for filter characteristics is presented.In this technique the characteristic function is composed of the rational function constructed by Chebyshev polynomial and coefficients related to frequency. Thus the attenuation characteristics close to thos of elliptic filter for the same order are obtained. The computing results show that the technique of non-equiripple approximation has advantages over Chebyshev filter and inverse Chebyshevfilter. The design procedure is not only clear in theory,but also simple and easy to complete computer program. The approximation method based on non-equiripple is an intermediary between equiripple approximation and maximally flat approximation. It is quite useful for filter design.