Design Flow In VLSI

July 20, 2017 8:43 am Published by 1 Comment


Dear Readers,

Ever wondered about how those chips present in almost every electronic components are manufactured and how even a very complex function is performed in seconds using these structures having lots of interconnected lines and dots. Well here comes VLSI (Very Large Scale Integration).

The VLSI circuits contains millions of gates on a single chip, don’t get surprised ! Yes its millions , which are manufactured using a definite methodology. A definite design flow is followed containing various steps. The Design flow comprises of two broad steps : Front End Design and Back End Design.

VLSI Design Flow

Block Diagram for VLSI Design Flow

Front End Design :

The front end design consists of those steps which involves manufacturing only on softwares and functionality verification. It consists of following steps :

  • Design Specification : According to the requirements, they describe abstractly the architecture, functionality and interface of the digital IC circuit to be designed. The object is to describe the purpose of the design including all aspects, such as the functions to be realised, timing constraints, and power dissipation requirements etc.


  • Beahvioural Description : Behavioral description is then created to analyze the design in terms of functionality, performance, compliance to given standards, and other specifications.


  • RTL Description : RTL description is done using HDLs and simulated to test functionality.We need the help of EDA tools from here onwards. The various substeps include verification of functionality and tesing on a software. At the end, the design is synthesized using the EDA tools and various timing constraints are checked.


vlsi design-2

Back End Design :

  • Gate – level Netlist : RTL description is then converted to a gate-level netlist using logic synthesis tools. It is a description of the circuit in terms of gates and connections between them, such that they meet the timing, power and area specifications. The design is partitioned into convenient compartments or functional blocks, placed on a silicon floor and various interconnects are routed on the chip.


  • Physical Layout : Finally a physical layout is made, which will be verified and then sent to fabrication.


Besides these three important parameters are to be kept in mind while designing the VLSI circuits-Power, timing and area . According to the specifications, one parameter is trade off above other. In order to tackle all these factor we have to consider as first priority what the consumer want if someone want more speed then he/she has to compromise with the power, and may be area it depends on architecture Overall, Power consumption and area should be minimized and timing should be as fast as possible.

The VLSI Design flow is a most general one. However different and efficient methodology is being found out to have an efficient manufacturing of VLSI circuits which are an unavoidable part of any electronic component. Obviously we want a more fast and swift system which should be implemented on a small chip area and having a consumption of very low power.

Keep Tuned To This Space For More. Happy Reading !!!

Harsha Thakur
Technical Content Writer

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