Physical Design Of The 144M DDR-SRAM Based On UMC 28 Nm

From the perspective of physical design,this paper analyzes two directions of academic significance in physical design,they are low power consumption and high performance.Combined with the practical work on physical design of a DDR-SRAM chip based on UMC 28 nm process,in this work shows the research aiming at the timing sequence requirement in DDRII design,that is to accomplish reading and writing in 1.5clock cycles and deal with the consumptiom problems.The research to achieve the requirement of high performance mainly focus on how to deal with the problem of long delay brought by the long length of metal connection nets in large area,and how to efficiently plan tens of thousands of critical paths for large capacity.The research contains via research on processing technology,appropriate Buffer and Inverter standard cells are chosen,along with innovative use of great quantity of high-level long metal nets to solve the problem of delay,appropriate metal layer and standard cells distance from each other,to achieve the timing closure which is difficult for automation tools and routine schemes.In addition,SRAM IP is grouped to make it modular.After the module is independently designed,it will be called at top level,which greatly reduces the workload.By the means of writing scripts to group and optimize paths that need to plan,workload is reduced due to avoiding manual operation for each,and solidification of scripts can facilitate subsequent version iteration as well.The research shows that the power plan of physical design is also one of the focuses discussed.In this work,the power domain division and implementation in the design are described in detailed,including the power supply plan within the module,and the top-level power supply plan scheme for the module alone.In addition,to timing requirement,when faced with vast high-metal resources occupied by signal nets,selection of suitable positions to supplement power stripes and ground stripes can make the design satisfy power consumption requirement.By using design schemes introduced above,after the design work is completed,a serial of checks of timing,design rules,power consumption,consistency,etc.for physical design can be passed through.Under the condition that all requirements are met,GDS will be delivered for taping out.