The Implementation And Application Of FIR Filter Based-on Distributed Arithmetic

Real-time, high-speed and reliability are the ultimate pursuit of digital signal process. TheFIR digital filter is critical to real-time signal processing due to strictly linear phase character.Structures of convolution type and direct type are initially used to design the FIR filters, whichneed many adders, shifters and multipliers. However, by this method, resource utilization is nothigh,and the processing speed is slow. In order to solve the above problems, Ruduced AdderGraph (RAG) algorithms and Distributed Algorithms (DA) are put forward. The look-up tablestructure of FPGA is very suitable for the realization of distributed arithmetic. Therefore,developing the design and research of FIR filter and realizing its function based on FPGA hasgood prospects.In this paper, some research about the design and implementation of FIR filter based onDA are introduced. Based on the two-dimensional (2-D) distributed structure of FIR filterpresented by Meher, some improvements were made in order to improve the resource utilizationof digital filters and ensure timing synchronization of the output under synchronous clock,which included adding delay modules and binary weight multiplication(*2n) to replace shift andaddition structure. According to the above, two structures were designed—"time-delayingtype" and "improvement type". The two structures were implemented on FPGA. Some filters,of which the order was M=3,7,9,15,31,63were designed respectively using the two structuresabove, so as to compare the performance of the two types. Testing the "improvement type" byusing board of DE2and A/D&D/A card. The experimental results illustrate that the filter canfilter the bandstop signal and keep passband signal not changed. It implements the purpose ofband pass filter.According to the above, the paper continues to explore the practical application of theimproved FIR filter. Type I high-pass filter based on "improvement type" replace the high-passfilter of audio chip (WM8731) on DE2board, so as to verify a filter's operability based onimproved DA in practical application. When testing, the input signal which is audio signalmixed with noise go through the filter. As a result, at the output get a clear audio signal.