Fast Fourier Transform (FFT) is one of the most widely
used algorithms in digital signal processing. It is used in
many signal processing and communication applications.
many of the FFT operations are performed in embedded
systems. Since Embedded systems is very small proces-
sors used in almost all type of appliances from microwave
ovens to cars, and many embedded systems are portable
and depend on small batteries for power; low energy de-
sign is extremely important in embedded systems design.
One of the major energy consumption sources in any pro-
cessor is memory access. Memory access requires more
energy than almost any operation in a DSP (Digital Sig-
nal Processor), or embedded processor, reducing memo-
ry access plays a very important role in reducing energy
consumption. In this paper we concentrate on the energy
consumption in memory in calculating FFT. we compare
between three different techniques in calculating FFT
with reference to energy consumption in memory access.
We also investigate the effect of the number of registers in