On Routing Architecture for Hybrid FPGA

In this paper, the routing architecture for an FPGA with hybrid clusters built from a mixture of LUT-based and PLA-like blocks is investigated. The implemented CAD flow that is used to place and route a number of MCNC benchmark circuits in a comparative fashion is discussed. The experimental results demonstrate that cluster sizes of two (2 LUT blocks and 2 PAL blocks) to four (4 LUT blocks and 4 PAL blocks) are appropriate in terms of area and speed. A comparison between hybrid and LUT-based FPGA architectures is also presented, showing that hybrid FPGA has some considerable advantages over a uniform LUT-based architecture.