设计一巴特沃兹带通滤波器，其３dB边界频率分别为f2=110kHz和f1=90kHz，在阻带f3 = 120kHz处的最小衰减大于10dB，采样频率fs=400kHz。-Design of a Butterworth band pass filter and the 3dB frequency boundary respectively and f1=90kHz f2=110kHz and in resistance with F3 = 120kHz minimum attenuation of