After a many days, I find some time to open up a word editor to put on my thoughts about VLSI, Since I am Master degree graduate in VLSI, and I am working in the field of VLSI, I plan to make a blog on the topic ”VLSI in a layman language”. In recent years, the term VLSI became a very fancy and talks of the town. When I was doing my undergraduate in electronics and communication, a decade ago, the term VLSI with respect to the tools and advance in technology make a popularity in midst of engineers. In this blog I plan to put up, what is my understanding about VLSI.
The term VLSI stands for Very large scale integration, which everyone will know by this time. What is actually VLSI? As like other engineering phases, VLSI too has Design, Verification and Implementation. The VLSI design starts with Requirement specification, which will be collected from the customer. The next will be deciding the architecture; it’s nothing but the high level (Block diagram) functionality of the circuit (Integrated Circuit (IC)). Following the architecture design, the architecture implementation using the EDA (Engineering Design Automation) tools is carried out. The first step in building the architecture is, implementation of the logics using Hardware description language. As in standard, we have two hardware description languages in use, VHDL (VHSIC (Very High Speed Integrated Circuits) Hardware Description Language) and Verilog HDL. The code written in the HDL which describes the circuit is known as RTL (Register Transfer Level), which means the lowest level of abstraction that can be described using HDL is the register level.
Once the Coding is done, the RTL needs to be verified in terms of functionality, power; area etc., the modern EDA tools provides more easy way to do these sophisticated processes. Now comes the question of FPGA or ASIC. What are these two things? FPGA stands for Field Programmable Gate Array and ASIC for Application Specific Integrated Circuit. On proceeding with the process of manufacturing the IC, few more steps are involved which will involve more cost and time. On manufacturing the functionality as IC, if there is any bug involved in the function, the whole effort will be wasted; hence FPGA provides the door step to build the prototype, to verify the functions before making the IC as Application specific. However, in some cases the Application specific IC may not be available. In such cases, FPGA can be directly used. Shown in figure is the ASIC manufacturing process.