Hardware efficient design of Variable Length FFT Processor

Proliferation of handheld devices and growing interests in pervasive computing has led to the need for more flexible communication solutions where a single device integrates various wired and wireless communication standards e.g. Asymmetric Digital Subscriber loop (ADSL), Very high speed Digital Subscriber Loop (VDSL), Digital Audio Broadcasting (DAB), Digital Video Broadcasting (DVB-T/H) and 802.11. In this paper, such a flexible communication solution is presented, applicable to all useful FFT processor lengths: 2ⁿ (n=6, 7...13) and implemented on a flexible platform: Field Programmable Gate Array (FPGA). The solution is optimized ensuring an efficient implementation with respect to resource usage whilst ensuring that the solution meets the throughput requirements of the individual standards. The key features of the efficient design include: a conflict free in-place memory replacement scheme for intermediate data storage; a dynamic address generator scheme and the CORDIC (CO-ordinate Rotational Digital Computer) technique for twiddle factor multiplication.