When only one butterfly PE is used to carry out the FFT, a RAM for
implementing the data input and output is a viable alternative. Figure 7.3.11
shows such a configuration. The PE requires two arguments. Thus, a dual
port memory is suitable. As can be derived from the signal flow graph in
Figure 7.3.1, memory with a capacity of N pieces of complex data in sufficient.
The results of a butterfly operation can be written back to the same
position in memory from which they were taken (in-place processing).The
control ROM must supply N different coefficients and the control signals.
The control signals essentially serve for memory addressing during the
processing phase. Special control extensions make simultaneous reading in the
results and storage of the new data possible at the end of each process.