A Memory-Based FFT Processor Design With Generalized Efficient Conflict-Free Address Schemes

This paper presents the design and implementation of memory-based fast Fourier transform (FFT) processors with generalized efficient, conflict-free address schemes. We unified the conflict-free address schemes of three different FFT lengths, including the single-power points, the common nonsingle-power points, and the nonsingle-power points applied with a prime factor algorithm. Though the three cases differ in terms of decomposition, they are all compatible with memory-based architecture by the way of the proposed address schemes. Moreover, the decomposition algorithm utilizes a method, named high-radix-small-butterfly (HRSB), to decrease the computation cycles and eliminate the complexity of the processing engine. In addition, an efficient index generator, a simplified multipath delay commutator engine, and a unified Winograd Fourier transform algorithm butterfly core were also designed. We designed two FFT examples in long-term evolution system to verify the availability of the address scheme, including a 2
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(128-2048)-point FFT unit and a 35 different point (12-1296) DFT unit. Compared with previous works with similar address schemes, this paper supports more generalized lengths and achieves more flexible throughput.