As we all know VLSI stands for Very large scale integration. Very large scale integration is the process of creating an integrated circuit by combining thousands of transistors into a single chip. Now the question comes why we need VLSI???? So the answer is that one of the most characteristics of information service is there increasing need for very high processing and band width. The other important characteristics is that the information service tend to become more personalized, which means that the information processing device must be more intelligent and also be portable to allow more mobility.
VLSI is mainly classified in two classes.
VLSI back end – VLSI back-end includes Route, place and floor planning. Back end includes development and fabrication part. It is too costly and time consuming process.Physical designing and layout refers to back end.
VLSI front end – VLSI Frontend includes designing and testing part. It uses Verilog and HDL, VHDL .RTL designing , minimizing delay and simulation refers to Front end.
There are two important steps . VLSI design and designverification. VLSI design refers to the designing of VLSI circuits and its implementation . Design verification is use to test the design and verify us that the given designing is working properly or not.
Now, we should move towards physical and digital design of VLSI. Both are very important part of VLSI.
Digital design is divided in three steps. First is BEHAVIORAL, second is STRUCTURAL and third one is PHYSICAL design. BEHAVIORAL describes the algorithm, STRUCTURAL describes component and their connections, PHYSICAL describes how circuit built.
In standard design cycle physical design comes after the circuit design. Physical design includes both design and verification and validation of layout. At this step circuit representation is converted into geometric representation.