Design and Implementation of a Digital Anti-Aliasing Filter using FPGA for Communication Systems

Abstract: In this paper, we discuss a practical way to synthesize and filter the base band signal in the background of different interference signals resulting from white noise placed within the signal band and sinusoidal interference signal placed out of the signal band. This will be done by a one digital filter of type FIR LPF with Hamming window by using a digital programmable device (Cyclone II EP2C70F896C6 FPGA from ALTERA) placed on education and development board DE2-70. This filter is designed using VHDL language within Quartus II 9.1 design environment. The proposed method depends on designing a set of DDFS to synthesis the base band signal and the various interference signals so the specifications of the base band signal become very closed from the real one, and designing a FIR LPF, so the result is removing all the interference signals and overcoming on the anti-aliasing phenomena by this digital filter. The FIR LPF operation results are studied by using a digital oscilloscope for input and output signals due to different sinusoidal interference signals and white noise in time and frequency domains.

Keywords: Anti-AliasingFilter, FIR LPF, DDFS, FPGA.