Home Tech Sanity Check In VLSI : Better Vision For Better Connection

Sanity Check In VLSI : Better Vision For Better Connection


Physical design engineers perform sanity checks to ensure that the inputs that get received for physical design are absolutely right and consistent. Any problems or hassles in the input files can cause problems in the later stages. So, it is critical to perform the sanity checks in the beginning stage, that is when the design stays loaded in the PnR tool and before the beginning of the floorplan. After all, the professionals have to ensure that the vlsi circuit is absolutely safe, effective and safe.

Criticality of sanity checks in VLSI 

Whether the design should proceed or not, it is something that is decided by sanity checks in VLSI.  The prime goal of such a testing is to make sure that the alterations or planned features are functioning as intended. On the failure of the sanity test, the testing team rejects the design-build to save absolute money and time.  The point is simple, even before the engineers start with their physical design cycle, they should run some sanity tests. Sanity checks promise that the information that is gathered from multiple teams, like the synthesis team as well as library team, is correct and proper. In case they simply are unsuccessful to carry out these tests, they may experience issues in the later stages. Now, if you are wondering about the input files that should be checked during sanity checks they can be like:


The consistency of Netlist should definitely be confirmed. This check evaluates the currently loaded netlist for any sort of inconsistencies and reports them. Of course, what is the point if you get to know about any such issues down the lane? It would be a waste of effort, time and money. so, performing this taste would help you understand about the flawlessness of the procedure.

SDC Files 

Before you begin the design, the SDC file should definitely be confirmed. Some of the most prevalent and popular SDC file issues can be like:

  • Registers powered by manifold clocks
  • Overall unrestricted route
  • The clock has simply reached all synchronous components.
  • Clock definition is absolutely missing.
  • Endpoint with no sort of constraints
  • A port’s input or output delay is missing.
  • A port’s slew or load restriction is absent.

Certainly, once you are aware of these issues and clear them in advance, you can be sure that you don’t have to face them later on. Whether professional engineers or a hardware designer, these tasks are important to be performed.

Check the library

Checking libraries authenticates the libraries i.e., it carries out consistency checks between logical and even physical libraries, throughout the logical libraries, and inside the physical libraries. This is the command that checks library qualities in three prime areas:

Library Files 

In the realm of the library check, one simply evaluates the libraries before starting the overall physical design by comparing the physical as well as logical libraries. It even examines the quality of both libraries as well as indicates any sort of blunders. The cells that are used in the design should definitely be present in both the logical and even physical libraries.

VLSI Design: Pre-Placement Sanity Checks encompass:

  • Undriven Input Ports
  • Pin direction mismatch
  • Proper timing
  • Checking physical type of constraints
  • Floating pins in the netlist
  • Unconstrained type of pins
  • PG grid check
  • Unload overall output ports

Importance of VLSI in Present Time 

If you are not really sure about the concept of VLSI then this post is going to give you a quick deep idea. Very large-scale integration or even VLSI is a process wherein millions of MOS transistors are joint and integrated on a single semiconductor microchip. With the global semiconductor revenue consistently growing, there is a great need to design and generate much efficient and specialised chips that can power new age technologies like AI/ML, AR/VR, IoT, Cloud etcThese are increasingly turning out to be mainstream instead of staying in niche technologies. Growth in consumer electronics, computing devices, even post pandemic, smartphones, intelligent vehicles and more has further enhanced the requirement. You know on the basis of the number of components (Transistors) to get integrated, ICs get categorised as MSI, SSI, LSI, VLSI, ULSI & even GSI.

  • Small Scale Integration (SSI): 1-100 Transistors got fabricated on a single chip. 
  • Medium Scale Integration (MSI): 100 to 1000 number of Transistors might get integrated on a single chip.  
  • Large Scale Integration: 1000 to 10000 transistors might be integrated on a single chip.  
  • Very Large-Scale Integration (VLSI): 10000 to 1 million Transistors might get accommodated.  
  • Ultra-Large-Scale Integration (ULSI): 1 millionth to 10 million Transistors might be accommodated.  
  • Giant Scale Integration (GSI): More than 10 million Transistors might be accommodated.  

Before VLSI, ICs might only perform a restricted number of functions and electronic circuits including a CPU, RAM, ROM, and other kinds of peripherals on a circuit board (PCBA). However, after this type of technology got introduced, millions of transistors and all even these functions can now get embedded into a single microchip. Hence allowing complex semiconductor and telecommunication technologies to get developed. You know the advancement in electronics is hugely due to the VLSI technologies and its quick adoption.

Quick perks of the VLSI you should know  

  • Circuit sizes get reduced 
  • Enhanced performance and speed
  • Demands less space
  • Demands less power and generates less heat
  • Effective expense reduced
  • Enhanced level of reliability

VLSI type of circuits are used everywhere, encompassing microprocessors in a personal computer, even chips in a graphic card, digital camera or even camcorder, chips in a cell phone, embedded processors, and even safety systems such as anti-lock braking systems in an automobile, personal entertainment systems, even medical electronic systems and more.


To sum up, you can make the most of this technology. Just speak with the printed circuit board manufacturers and ensure that you have the best options in hand. Right from proper sanity check to proper procedures; everything plays a critical role.