Low-power fast Fourier transform hardware architecture combining a split-radix butterfly and efficient adder compressors

Fast Fourier transform (FFT) is the most common low-complexity implementation of the discrete Fourier transform, intensively employed to process real-world signals in smart sensors for the internet of things. Butterflies play a central role as the FFT computing core data path since it calculates complex terms employing several multipliers. A low-power FFT hardware architecture combining split-radix decimation-in-time butterfly and 5-2 adder compressors (ACs) is proposed and implemented. The circuits are described in Verilog hardware description language and synthesized using the Cadence Genus synthesis tool. The circuits are mapped onto a 65-nm CMOS ST standard cell library. Results reveal that the proposed FFT hardware architecture using the split-radix butterfly is 13.28% more power efficient than the radix-4 one. The results further show that, by combining 5-2 AC within the split-radix butterfly, our proposal saves up to 43.1% of the total power dissipation considering the whole FFT hardware architecture, compared with the state-of-the-art radix-4 butterfly employing the adder automatically selected by the logic synthesis tool.