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Unformatted text preview: Chapter 2 Cadence DFII and ICFB C ADENCE is a large company that offers a dizzying array of software for Electronic Design Automation (EDA) and Computer Aided Design (CAD) applications. The custom design tutorials in Chapter 5 are a good starting point for custom analog IC design, too. Cadence CAD software is generally targeted at the design of electrical circuits, both digital and analog, and extends from extremely low-level VLSI design to the design of circuit boards for large systems. This book is primarily interested in digital integrated circuit (IC) design, so well look primarily at those tools from the Cadence suite. 2.1 Cadence Design Framework Many of the digital IC design tools from Cadence are grouped under a framework called Design Framework II ( DFII ). The DFII environment integrates a variety of design ac- tivities, including schematic capture ( Composer ), simulation ( Verilog-XL or NC Verilog ), layout design ( Virtuoso and Virtuoso-XL ), design rule checking (DRC) ( Diva and Assura ), layout versus schematic checking (LVS) ( Diva and Assura ), and abstract generation for standard cell generation ( Abstract ). These are all individual programs that perform a piece of the digital IC design process, but are all accessible (to a greater or lesser extent) through the DFII framework and the DFII user interface. Note that many of these programs were developed by separate companies that have been acquired by Cadence and folded into the DFII framework after that acquisition. Thus, some integrate better than others! As well see, though, there are some pieces of the Cadence tool flow that are not linked into the DFII framework. Most notably, place and route of standard cells with SOC En- counter , connection of large blocks with ICC Chip Assembly Router ( ccar ), and Verilog synthesis with RTL Compiler are done in separate programs with separate interfaces. However, well start with the DFII tools in this tool flow, so well need to start up the DFII framework. The executable in the Cadence tool suite that starts up this framework is 10 CHAPTER 2: Cadence DFII and ICFB called icfb , which stands for Integrated Circuit Front to Back design. If you were to set up your search path so that the Cadence tools were on your path and then executed the icfb command, you would see the DFII framework start up. Unfortunately, this wouldnt help you much! It turns out that having the tool framework is only half the battle. You also need detailed technology information about the devices you want to use for your design. This detailed design information includes technology information about the IC process that you are using and libraries of transistors, gates, or larger modules that you can use to build your circuits. This information includes many files of detailed (and somewhat inscrutable) information, and does not come from Cadence....
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This note was uploaded on 02/24/2011 for the course ECE 6710 taught by Professor Dr.erikbrunvand during the Fall '11 term at University of Utah.
- Fall '11