Design Of 5T2R In-Memory Computing Unit Based On RRAM

With the IC industry entering the “post Moore era”,the manufacturing process of semiconductors has made slow progress,resulting in the performance improvement of computers brought by the process progress of transistors is decreasing year by year.At the same time,the problems faced by the mainstream computer architecture and memory also exacerbate the above phenomenon.Among them,the problem of architecture is the speed difference between computing and storage units,while the problem of memory is the charge leakage in nano scale.The emergence of “RRAM in-memory computing” makes it possible to solve the above two problems.The in memory computing architecture realizes operation and storage in one unit at the same time,breaks the speed difference between operation and storage units,and improves the computing performance.Resistive random access memory(RRAM)stores data in the form of resistance,There is no charge leakage and the internal data will not be lost due to the removal of external power supply,which improves the stability of data storage in nano scale.Based on RRAM in memory computing,this paper designs a new in memory computing unit structure,which is roughly as follows: firstly,RRAM in memory computing is introduced from the limitations of traditional computing architecture and memory.Secondly,around the core device RRAM,its structure types and characteristics are summarized,the working mechanism of resistive state conversion of RRAM is analyzed,and the spice model of RRAM is given.Then,taking a typical RRAM in memory computing unit as an example,the application scenarios of the corresponding units are described.Finally,based on the above units,5T2 R storage and calculation unit is proposed.The new 5T2 R memory computing unit can realize basic storage and operation functions,including Boolean logic,three state addressing and semi subtractor.Boolean logic operation realizes “AND”,“OR” and “XOR”,and the operation uses the series and parallel connection of RRAM devices to alleviate the resistance state overlap problem of RRAM devices and improve the reliability of the unit in operation.Through the word line reconfiguration of 5T2 R unit,the three state addressing operation is realized.Based on the logic operation,the results are output from the separated source lines SL0 and SL2 to realize the half subtractor and expand the function of the unit.In addition,because the 5T2 R unit can form a transmission gate,its reset success rate is higher than that of1T1 R unit.The simulation analysis of 5T2 R unit under 28 nm process shows that 5T2 R unit can realize corresponding functions,solve the resistive state overlap of RRAM and improve the reset operation success rate by 10.3%.To sum up,this paper focuses on the functionality and reliability of RRAM memory and computing unit.On the basis of expanding the function of RRAM memory and computing,it alleviates the resistance state overlap problem of RRAM devices,reduces the probability of errors in unit operation,and provides ideas for the subsequent research on the functionality and reliability of RRAM memory and computing.