Radix-2 vs Radix-4 FFT Butterfly Structures

Radix-2:

x(0)

x(2)

x(1)

x(3)

X(0)

X(1)

X(2)

X(3)

Stage 1

Stage 2

Radix-4:

x(0)

x(2)

x(1)

x(3)

X(0)

X(1)

X(2)

X(3)

Stage 1

Each butterfly requires:

8 Memory accesses

4 Multiplications

6 Additions

Each butterfly requires:

16 Memory accesses (4 / R-2 bfly)

12 Multiplications (3 / R-2 bfly)

22 Additions (5.5 / R-2 bfly)

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