An Efficient FFT Processor for DAB Receiver Using Circuit-Sharing Pipeline Design

With the upcoming fourth generation wireless systems and convergence of multiple radio standards into a single terminal, building blocks are needed that can be configured for computing various algorithms used in different standards. Given these trends and requirements, in our previous paper we successfully proposed a circuit-sharing design for the DAB receiver to integrate the FFT (fast Fourier transform) and IMDCT (inverse modified discrete cosine transform) operations into the same functional circuit. The proposed technique reduces hardware overhead, enhances circuit efficiency and significantly reduces the cost of DAB receivers. To further improve the efficiency of our previous work, this investigation proposes another alternative design named the circuit-sharing pipeline design (CSPD) using a single processor with a pipeline scheme to combine two functions, FFT and IMDCT, into the same circuit. The proposed method reduces the required chip area and cost of DAB receivers. Analyzing the existing relationship among IMDCT, DCT (discrete cosine transform) and FFT, the IMDCT function can be replaced using a FFT function. Therefore, it is not necessary to design an extra circuit for IMDCT. The arithmetic unit in the FFT processor can be significantly reduced due to employing the pipeline scheme. Consequently, the circuit redundancies in the IMDCT and FFT functions can be easily eliminated to allow exploitation of the decreased chip area. Results of this study demonstrate that the proposed design can provide advantages such as low gate count and small memory size in the DAB (digital audio broadcasting) receiver.