The Test System Design Based On RRAM’s DMA Mode

With the development of economy and the advancement of technology,NVM is becoming more and more important.As the representative of NVM,FLASH memory is widely used in various fields.However,due to the limit of the minimum process size,the development prospect of FLASH is not optimistic.On account of its superior characteristics including excellent scalability,high density and fast speed,RRAM is very likely to replace FLASH and become new main strem NVM.Nowadays,after the RRAM being producted,its testing is mainly realized by commercial automatic test equipment.But,there are many problems,such as complex operation,high cost,poor practicability and so on,which make RRAM’s research cycle from design to massly production greatly prolonged.In general,the RRAM has DMA(Direct Memory Access)mode and user mode.The DMA mode is direct memory access,it’s specially designed for test purpose.User mode is the mode in which the user actually uses RRAM to read and write data.Based on the above considerations,the research work of this paper is to design the RRAM special test system to solve the problem in RRAM test.The test system has many advantages such as good applicability,simple operation,low cost and reliable performance,which can greatly reduce test costs for RRAM research organization and accelerate the development of RRAM.In the beginning of the paper,it introduces the research status of commercial automatic test equipment and discusses the technical problems of RRAM test.Secondly,elaborates the basic principle of RRAM and the test method of RRAM in DMA mode.Based on these,the communication protocol and test fow are defined,then a test system based on RRAM’s DMA mode is designed.The test system wih DC parameter measure module has 30 driving channels and a receiving channel,which can perform basic tests like forming,reset and set for RRAM cell.It is composed of upper computer,FPGA,four channel parameter measurement unit(AD5522)and high pecision digital to analog converter(AD7685).This paper elaborates the core part of the test system--FPGA’design,on the basis of ATE communication protocol and test process,the FPGA architecture is proposed and the module partion in detail is completed.And then detailed design the communication module,send module,system control module,AD5522 control module and AD7685 control module.By using ISE and Modelsim,the verilog code and simulation of each module are completed.Again,the hardware of the test systerm was debugged and ist measure function is verified.Finally,the full text is summarized and the ameliorating direction is pointed out.