cic

代码说明：

  当前工程上广泛采用了一种高效滤波器，即CIC（cascaded integrator-comb filter）将其作为第一级来实现抽取、低通滤波。第二级再用一个普通的FIR滤波器就实现使后端设备工作在较低的频率下且硬件花销少、功耗也很低。(Widely used in the current project, a highly efficient filter, that is, CIC (cascaded integrator-comb filter) as the first level to achieve the extraction, low-pass filter. An ordinary second-class and then the realization of the FIR filter so that the work of the back-end equipment at a lower frequency and spending less hardware, power consumption is very low.)