Using Negative Edge Triggered FFs to Reduce Glitching Power in FPGA Circuits

This paper presents an algorithm for reducing dynamic power dissipated by Field-Programmable Gate Array (FPGA) circuits. The algorithm uses a fast probability based model to estimate glitches on wires in a circuit and then inserts negative edge triggered FFs at outputs of Lookup Tables (LUTs) that produce glitches. A negative edge triggered FF maintains the logic value produced by the LUT in the previous cycle for the first half of the clock period, filtering glitches that occur at the output of the LUT. The power dissipation is lowered by reducing the number of transitions that propagate to the general routing network. We applied the algorithm to a set of benchmark circuits implemented on a commercial FPGA, Altera´s Stratix II. The results obtained using Quartus II 5.1 CAD tool show a reduction in dynamic power dissipation by 7% on average and up to 25%.