Design And Implementation Of Reconfigurable PIM Computing Unit

Processing-in-Memory,which places the steps of processing into the main memory,is one of the future solutions to the “Memory Wall” issue of Von Neumann architecture,and PIM architecture based on memristor cross-bar array is a hot direction.The researches of memristor based PIM structure are going into two ways: analog and digital.Parallel analog multiply accumulate operation(MAC)can be applied to memristor cross-bar array effectively,while memristors can play a role that similar to CMOS in logic gate circuits due to its unique resistance characteristic,composing structures that similar to FPGAs or ALUs with the advantages of PIM.The memristor cross-bar array based PIM architectures that focus on analog computation can only provide support for applications that require mass analog MAC and tolerate the inaccuracy brought by analog computation.It is hard for them to change their architecture to meet the requirements of application that need different computing resources,thus this kind of architecture is hard to aim at general-use architecture.The architectures that focus on digital logic operations are developed as general-use processing unit with PIM's characteristic,but they give up nature memristor cross-bar array's advantage of executing analog MAC as the price.To solve this problem,a new PIM computing unit is put forward which takes the advantages of both two sides and meet different applications' needs to the hardware resources in this thesis.It provides a foundation for the design of a general-used reconfigurable PIM architecture.In this thesis,the functional requirements of general-used reconfigurable PIM computing unit are analyzed from the recent works.The computing unit is dynamic reconfigurable,which enabling the computing unit to switch flexibly among three functions when needed:1)Single bit/multi-bit data storage,2)Parallel digital logic operation with PIM support,3)Analog MAC operation,providing reconfigurable PIM support for the applications that requiring different computing resources in various fields.In this thesis,code and circuit of main modules are designed,and computing unit is built in simulation environment.Functions including read/write,logic function and MAC are tested and evaluated.Results show that the PIM reconfigurable computing unit presented in this thesis has the comprehensive advantages of speed and energy consumption comparing to the computer when executing massive simple digital logic operation and analog MAC.The speed of full-adder reaches the microsecond level.