Area Efficient Architecture for Frequency Domain Multi Channel Digital Down Conversion for Randomly Spaced Signals

A complete frequency domain processing based digital down conversion architecture is presented in this paper. The conventional complex NCO multiplication is achieved with direct spectrum rotation and various possibilities for frequency domain filtering are discussed. An FFT-IFFT based architecture is implemented in Xilinx Virtex-6 family XC6VLX240T FPGA platform and synthesis is verified. The overlap and add method at the output of IFFT is employed to avoid time domain overlapping. The results demonstrate highly optimized area implementation with respect to conventional DDC architectures. The synthesis results show that the developed core can work upto clock rates of 250 MHz while occupying only 10% of the FPGA slices.