Skip to main content

Standard-Cells Based Design

A standard cell based design needs development of a full custom mask set. The standard cell is additionally referred to as the polycell. In this approach, all of the commonly used logic cells are developed, characterized and stored during a galvanic cell library.

A library may contain a couple of hundred cells including inverters, NAND gates, NOR gates, complex AOI, OAI gates, D-latches and Flip-flops. Each gate type are often implemented in several versions to supply adequate driving capability for various fan-outs. The inverter gate can have standard size, double size, and quadruple size so as that the chip designer can select the proper size to urge high circuit speed and layout density.

Each cell is characterized consistent with several different characterization categories, such as,

• Delay time versus load capacitance

• Circuit simulation model

• Timing simulation model

• Fault simulation model

• Cell data for place-and-route

• Mask data

For automated placement of the cells and routing, each cell layout is meant with a hard and fast height, in order that variety of cells are often bounded side-by-side to make rows. The power and ground rails run parallel to upper and lower boundaries of cell. So that, neighbouring cells share a standard power bus and a standard ground bus. The figure shown below may be a floorplan for standard-cell based design.


 









Comments

Post a Comment

Popular posts from this blog

INTRODUCTION TO VLSI and Y chart

 Very-large scale integration (VLSI) is the process of incorporating thousands of transistors into a single chip to create an integrated circuit (IC) . VLSI got its start in the 1970s, when complex semiconductor and communication technologies were being developed.   The  microprocessor  is a VLSI device. A limited set of functions were performed by most ICs prior to the introduction of VLSI technology. An electronic circuit contains a CPU, ROM, RAM, etc. IC designers can integrate all of these functions into a single chip using VLSI. Thanks to rapid advancements in large-scale integration technologies and device design applications, the electronics industry has grown at a breakneck rate in recent decades.Since the introduction of very large scale integration (VLSI) designs, the number of integrated circuits (ICs) used in high-performance computing, controllers, telecommunications, image and video processing, and consumer electronics has been increasingly growing...
1 comment
Read more

Concepts of Regularity, Modularity and Locality

        By splitting the large structure into many sub-modules, the hierarchical design approach eliminates design complexity. To make the process easier, other design principles and approaches are usually needed. Regularity ensures that a large system's hierarchical decomposition can produce as many simple and identical blocks as possible.The design of array structures made up of similar cells, such as a parallel multiplication array, is a good example of regularity. Regularity can be seen at all levels of abstraction: uniformly sized transistors simplify the design at the transistor stage. Identical gate structures can be used at the logic level, and so on.      The different functional blocks that make up the larger structure must have well-defined functions and interfaces, which is referred to as modularity in design. Since there is no doubt about the purpose and signal interface of these blocks, modularity allows each block or module to be co...
2 comments
Read more

Historical Perspective

  The electronics industry has developed at a breakneck pace over the last two decades, owing primarily to rapid advancements in integration technologies and large-scale systems design - in other words, the introduction of VLSI. The number of integrated circuit applications in high-performance computing, telecommunications, and consumer electronics has been steadily increasing at a rapid rate.The requisite computational power (or, in other words, intelligence) of these applications is typically the driving force behind the field's rapid growth. The need to incorporate these functions in a small system/package is growing as more complex functions are needed in various data processing and telecommunications devices. For almost three decades, the degree of integration, as calculated by the number of logic gates in a monolithic chip, has been steadily increasing, owing to rapid advances in processing and interconnect technology.The given figure shows the evolution of logic complexity...
Post a Comment
Read more