数字低通滤波器频率特性的仿真研究

Simulation Research on the Frequency Characteristic of Digital Lowpass Filter

利用MATLAB语言的方法设计巴特沃思数字低通滤波器和切比雪夫数字低通滤波器,并对两种滤波器的频率特性进行了仿真比较,结果表明:在同样阶数下,切比雪夫低通滤波器的通带到阻带的变化比巴特沃思低通滤波器陡峭,因此,切比雪夫滤波器和理想滤波器的频率响应曲线之间的误差最小,但是在通频带内存在幅度波动。从实现的难度来看,巴特沃思滤波器更容易些,而且从相频的特性来说,巴特沃思滤波器比切比雪夫滤波器特性好,尤其在靠近边界频率处。

Using matlab language to design the Buttworth digital lowpass filter and Chevbyshev digital lowpass filter was designed and the characteristic of the two filter by simulation was compared.the results,showed that the change of Chevbyshev filter from pass band to cut off band is craggedness than Buttworth filter,so the error of the frequency respond curve between Chevbyshev filter and ideal filter is the least,but it is fluctuate in the transmission band.Buttworth filter is easier to realize by in difficulty of realization and the characteristic is better than Chevbyshev filter as to the phase-frequency characteristic,especially near the critical frequency.