Full-custom design in VLSI is a method of creating integrated circuits that specifies the architecture of each individual transistor as well as their interconnections. Various kinds of semi-custom design, such as the repeating of tiny transistor subcircuits. These are alternatives to full-custom design; one such method is the use of common cell libraries. standard cell libraries are designed using full-custom design techniques themselves.
What is the use of full custom design in VLSI?
Full-custom design has the ability to improve chip performance while reducing its size, but it is exceedingly time-consuming to achieve. Full-custom design in VLSI is restricted to ICs that are mass-produced in large quantities, such as some microprocessors and a small number of ASICs.
Also read : A brief overview of ASIC Design Flow
The back-end design of layout implementation, known as an integrated circuit (IC) layout, is separated into two categories: ASIC-style flow and full-custom flow. Full-custom design in VLSI implies a polygon-level layout done fully with basic polygon pusher software for a newbie to VLSI design. Many individuals execute this activity all throughout the world, and conventional thinking holds that the only way to increase the quantity and speed of layout is to recruit more people.
What are the types of Full custom design in VLSI?
In actuality, there are four different types of full-custom layout design, each with its own set of automation options:
Datapath Layout:
It is a full-custom layout dictated by space constraints or specific application requirements. A datapath with strict control over the area, signal noise, and bit symmetry is made up of repetitive sophisticated components like sense amplifiers, decoders, adders, and multipliers. This style of arrangement is known as “datapath layout.”
Analog Layout:
It is a completely customized architecture for high-performance or analog circuitry. This comprises phase-locked loops (PLLs), digital-to-analog converters (DACs/ADCs), electrostatic discharge (ESD) architectures, regulators, RF speed requirements, and low-power approaches. This style of layout is referred to as “analog layout.”
Also Read: What is the Antenna Effect in VLSI
Custom Digital Layout:
It is a complete-custom layout that demands more attention to space and performance than the full digital (ASIC) flow, but with fewer speed requirements and less need for device-level layout control than datapath or analog layout: This is referred to as a “custom digital layout.”
Cell Layout:
It is a fully customized cell development layout where cells are logical building elements that belong to a group of components with similar abutment rules, performance characteristics, or functionality. Cells in a conventional cell library or a family of Pad cells are two examples. This style of the arrangement will be referred to as “cell layout”.
Final Thoughts
This brief classification of the full-custom layout should aid the reader in making better selections about the tool to use for their assignment. Simultaneously, providers may acquire the necessary vocabulary and assist users in viewing the relevant demos for the tools they require from the Chipedge, which is one of the best VLSI training institutes in India. At Chipedge you can find a variety of VLSI courses online, such as ASIC Design Verification Course, Physical Design Course . Get enrolled, to have a better understanding of VLSI topics.
