The Impact of Low-Power Design Methodology on Digital Libraries

Abstract

In recent years, exciting new low-power design methods have been introduced, such as: multiple supply voltages, body bias techniques and power shut-off. In order to use these low power design methods, strict requirements for both libraries and tools are needed. An additional challenge is the introduction of more accurate characterization models for newer technologies (current source models like ECSM and CCS). This has made the task of library checking a serious issue that needs to be automated. The main part of this thesis presents a checker tool that is used to verify the consistency of the different library formats (views) in standard cell libraries. The layout consistency checker in our tool checks the consistency of the layout of pins between GDSII and LEF library views; we devised a new algorithm,Grid Formation and Centre Inclusion, for this checker. The tool also verifies the pin consistency and availability of cells across other library formats, such as: Verilog and Liberty. The tool was tested using different technology libraries (such as 90nm and 40nm), provided by different vendors (such as GLOBALFOUNDRIES); multiple interfacing errors were caught using our library checker tool. A second part at the end of the thesis shows experiments with some of the low-power design techniques used during the design of a digital block, using -for implementation- standard cells from one of the libraries that have been checked with the library checker tool. Benefits of using these techniques are evaluated and trade-offs are discussed. Power-Shut Off (PSO) design technique proved to be the most effective in reducing power consumption, with power savings that reached 20%.