设计一个切比雪夫滤波器，要求通带截止频率 ，通带最大衰减 ，阻带截止频率 ，阻带最小衰减 。要求绘出滤波器的幅频特性曲线。-Design a Chebyshev filter, the passband cutoff frequency required, the maximum passband attenuation, stopband cutoff frequency, stopband minimum attenuation. Requirements of the filter amp