| With the application and development of digital signal processing technology,the data that needs to be processed is becoming more and more quantitative in the system and there is a higher requirement for the speed.In order to reduce the amount of storage and computation in the process,the sampling rate in the system usually needs to be processed,and transform the single rate system into the multirate system.In recent years,with the rapid development of integrated circuits,the sampling rate of the signal is increasing,therefore,the multirate signal processing has been widely used.The multirate filter has the advantages of reducing the transmission rate,the computational complexity and the storage capacity.In this paper,the integrated cascade comb(CIC)filter is studied and implemented.The structure of 5 level cascades can meet the requirements of stopband attenuation greater than 60 d B,at the same time,the Noble identity is introduced into the structure,which can effectively reduce computation and save hardware resources.The implementation of CIC filters mainly includes three aspects: decimation,interpolation and low pass filtering.First,the theoretical basis of multirate signal processing and the structure and performance of the CIC filter are analyzed,and the implementation structure of the CIC filter in this design is determined;then,the Matlab is used to design and analyze the CIC decimation and interpolation filters,and the simulation is carried out;finally,a scheme of FPGA implementation of CIC decimation and interpolation filter is given,the Modelsim is used to simulate FPGA design,and the simulation results of Modelsim are analyzed under the Matlab environment,and the Modelsim simulation results are compared with Matlab simulation results to verify the correctness of the design.The simulation results show that the CIC decimation and interpolation filter can satisfy the requirement of 5 times decimation and 5 times interpolation for the original signal,the sampling rate is effectively reduced to 1/5 times and increased 5 times. |
