Direct sigma-delta modulated signal processing in FPGA

The effectiveness of implementing bit-stream signal processing (BSSP) multiplier circuits in FPGAs, in terms of hardware resources and clock frequency, is presented. In particular, the result of realizing BSSP multipliers on FPGA architectures that utilize 6-input lookup tables (LUTs) is compared against architectures that utilize 4-input LUTs. It is found that architectures featuring 6-input LUTs suit well in BSSP applications where wide combinatorial paths are common. Furthermore, the performance of a BSSP multiplier is compared against conventional parallel multipliers in terms of LUT resource requirements. For a given resource requirement, it is found that an over-sampling ratio of less than 32 is required for a BSSP multiplier to outperform its parallel counterpart.