一种数字式带通滤波器的级联设计法

A Cascade Design of Digital Bandpass Filter

以一模拟带通滤波器为基础，通过双线性变换获得了一种ＩＩＲ数字带通滤波器，导出了该滤波器系数与其中心频率及带宽的数学关系式．以此滤波器为原型滤波器，文中给出了一种ＩＲ数字带通滤波器的级联设计法．根据设计指标，可用文中给出的设计公式求出ＩＲ级联数字带通滤波器中原型滤波器的级数和带宽，从而最终确定ＩＲ级联数字带通滤波器．该滤波器具有系数少、结构简单、设计快等优点，很适合于数字带通滤波器的ＤＳＰ实现．

A prototype IIR digital bandpass filter is derived from an analogous bandpass filter by using bilinear transformation. The formulas relating the digital bandpass filter's coefficients with its center frequency and bandwidth are obtained. Using N sections of such digital bandpass filter, a cascade IIR digital bandpass filter is constructed. Based on the specifications and the formulas given, the parameter N and bandwidth of prototype IIR digital bandpass filter can be obtained, and the unknown cascade IIR digital bandpass filter can be finally determined. The filter has few coefficients and a simple structure and it is easy to be designed. It is especially suitable for its implementations when using DSP.