Delay evaluation of 90nm CMOS multi-context FPGA with shift-register-type temporal communication module for large-scale circuit emulation

For large-scale circuit emulation with using a multi-context FPGA (MC-FPGA), a circuit is divided into multiple sub-circuits, each sub-circuit is assigned to a context., and the MC-FPGA sequentially executes all the contexts one by one. So, the total execution delay is the sum of the delays of the contexts. It is, therefore, said that the total execution delay of the MC-FPGA increases proportional to the number of contexts used. However, in this paper, we show that the total execution delay remains constant if a shift-register-type temporal communication module (SRTCM) is used instead of D-flipflop (D-FF) to implement sequential circuits. The SR-TCM is used not only for signal communication of sequential circuit like D-FF, but also for signal communication from preceding context to succeeding contexts. In order to quantify the delay, a MC-FPGA named flexible processor (FP), which contains the SR-TCM, have been designed and fabricated in 90 nm CMOS process technology. From the measurement results, the total execution delay of the FP was kept constant regardless of the number of contexts used.