  The need for wireless communication has driven the communication systems to
high performance. However, the main bottleneck that affects the communication
capability is the Fast Fourier Transform (FFT), which is the core of most
modulators. This study presents an on-chip implementation of pipeline
digit-slicing multiplier-less butterfly for FFT structure. The approach is
taken, in order to reduce computation complexity in the butterfly,
digit-slicing multiplier-less single constant technique was utilized in the
critical path of Radix-2 Decimation In Time (DIT) FFT structure. The proposed
design focused on the trade-off between the speed and active silicon area for
the chip implementation. The new architecture was investigated and simulated
with MATLAB software. The Verilog HDL code in Xilinx ISE environment was
derived to describe the FFT Butterfly functionality and was downloaded to
Virtex II FPGA board. Consequently, the Virtex-II FG456 Proto board was used to
implement and test the design on the real hardware. As a result, from the
findings, the synthesis report indicates the maximum clock frequency of 549.75
MHz with the total equivalent gate count of 31,159 is a marked and significant
improvement over Radix 2 FFT butterfly. In comparison with the conventional
butterfly architecture, the design that can only run at a maximum clock
frequency of 198.987 MHz and the conventional multiplier can only run at a
maximum clock frequency of 220.160 MHz, the proposed system exhibits better
results. The resulting maximum clock frequency increases by about 276.28% for
the FFT butterfly and about 277.06% for the multiplier. It can be concluded
that on-chip implementation of pipeline digit-slicing multiplier-less butterfly
for FFT structure is an enabler in solving problems that affect communications
capability in FFT and possesses huge potentials for future related works and
research areas.
