低通滤波器允许从直流到某个截止频率(fCUTOFF) 的信号通过。将通用滤波器二阶传递函数的高通和带通系数均设为零，即得到一个二阶低通滤波器传递公式-The low pass filter allows the signal to be passed through the DC to a certain cutoff frequency (fCUTOFF). The high pass and band-pass coefficients of the two order transfer function of the universal filter are set to zero, that is, a two order low pass filter is obtained.