Multiplexer restructuring for FPGA implementation cost reduction

This paper presents a novel synthesis algorithm that reduces the area needed for implementing multiplexers on an FPGA by an average of 18%. This is achieved by reducing the number of lookup tables (LUTs) needed to implement multiplexers. The algorithm relies on reimplementing 2:1 multiplexer trees using efficient 4:1 multiplexers. The key to the algorithm's performance lies in exploiting the observation that most multiplexers occur in busses. New optimizations are employed which pay a small cost in logic that is shared across the bus to achieve a reduction in the logic required for every bit of the bus.