Design Of32×32Bits Three-port Hardened Register File

With the development of technology, integrated circuit used in the spaceenvironment is more and more, however, with technology scaling down, the rate ofsoft error in IC become larger in radiation condition. The register file is a keycomponent and a frequent access in CPU. If the soft error occurs in register file, theentire system will suffer the serious loss. Therefore, protecting register file againstradiation is essential. This design is a32×32bits three-port hardened register fileused in LEON3processor for high radiation space environment.In this paper, a strengthening scheme for protecting register file against SingleEvent Upset (SEU) and Single Event Transient (SET) is proposed after comparisonand analysis of the different strengthening way for register file. Then the memorycell array and peripheral circuit of three-port register file have been designed.Memory cell based on DICE structure is revised, which well realizes the function oftwo reading and one writing, at the same time, the noise margin is large enough andthe delay time of reading and writing is smaller than before. Besides, memory cellcould be immune to SEU by using revised DICE structure. The peripheralcombination circuit is strengthened through using C-element unit, and it possessesan excellent ability against SET. At last, the construction and the circuit simulationfor the whole circuit of register file is implemented.At last, a32×32bits three-port hardened register file which is used in LEON3processor is implemented and validated in SMIC0.18μm CMOS technology inlayout design. Post simulation results show that when the register file work at100MHz and the temperature is27℃with1.8V power supply, the function of2-read1-write can be implemented, and SEU, SET can be eliminated at the sametime. Compared with the Hamming coding hardening way, the design has higheranti-radiation ability and faster velocity.