Switch-based Fast Fourier Transform processor

Abstract

The demand for high-performance and power scalable DSP processors for telecommunication and portable devices has increased significantly in recent years. The Fast Fourier Transform (FFT) computation is essential to such designs. This work presents a switch-based architecture to design radix-2 FFT processors. The processor employs M processing elements, 2M memory arrays and M Read Only Memories (ROMs). One processing element performs one radix-2 butterfly operation. The memory arrays are designed as single-port memory, where each has a size of N/(2M); N is the number of FFT points. Compared with a single processing element, this approach provides a speedup of M. If not addressed, memory collisions degrade the processor performance. A novel algorithm to detect and resolve the collisions is presented. When a collision is detected, a memory management operation is executed. The performance of the switch architecture can be further enhanced by pipelining the design, where each pipeline stage employs a switch component. The result is a speedup of Mlog2N compared with a single processing element performance. The utilization of single-port memory reduces the design complexities and area. Furthermore, memory arrays significantly reduce power compared with the delay elements used in some FFT processors. The switch-based architecture facilitates deactivating processing elements for power scalability. It also facilitates implementing different FFT sizes. The VLSI implementation of a non-pipeline switch-based processor is presented. Matlab simulations are conducted to analyze the performance. The timing, power and area results from RTL, synthesis and layout simulations are discussed and compared with other processors.