Bit-Slice Butterfly Processing Units for 64-Point RSFQ FFT Processors

In this article, 8-bit bit-slice butterfly processing units (BPUs) are proposed for 64-point rapid single-flux-quantum (RSFQ) fast Fourier transform processors. The BPUs are based on radix-2, mixed-radix, and split-radix algorithms, respectively. Unlike the previously developed bit-serial RSFQ BPUs, the proposed bit-slice BPUs continuously process 64-point data divided into eight slices of eight points each in order to reduce the hardware cost. The BPUs use synchronous concurrent-flow clocking and they can be extended to any $n^2$ -point processing.