Role of SystemVerilog Assertion in Formal Verification
McKinsey & Company predicts that by 2030, the semiconductor sector will be worth a trillion dollars. With the increasing demand for semiconductors, it becomes important now more than ever to ensure the correctness and reliability of complex semiconductor chips. One of the crucial techniques that emerged for this process is formal verification. SystemVerilog Assertion(SVA) plays a vital role in formal verification providing a concise and expressive mechanism to specify the desired behavior of a design. In this article, we will delve into the role of SVA in the process of formal verification.
What is SystemVerilog Assertion?
SystemVerilog is a hardware description language employed in digital design to design and verify electronic circuits. It is an extension of the Verilog HDL and provides several new features.
SVAs are statements that describe the desired behavior of a design. These assertions, expressed in the SystemVerilog language, provide a concise and expressive way to specify properties that a design must satisfy, encompassing temporal logic, safety properties, and liveness properties. Formal verification tools leverage these assertions to check whether the design adheres to the specified behavior, ensuring its adherence to its functionality. If the design does not display the specified behavior, the assertion fails, pointing to a behavior problem in the design.
Types of SystemVerilog Assertions
These assertions are checked as soon as they are encountered in the simulation. They are typically used to check for errors or violations that should be detected immediately. For example, an immediate assertion could be used to check that a signal does not change value more than once in a single clock cycle.
These assertions are checked throughout the simulation, and they can be used to check for properties that may take time to develop. For example, a concurrent assertion could be used to check that a certain sequence of events always occurs.
What Information Does SystemVerilog Assertions Provide About the Design?
In formal verification, SVAs play a crucial role in verifying and validating the behavior of the design. By using SVAs, verification engineers can formally check the following aspects of an RTL design.
Corner Case Detection
Detecting corner cases is an important part of formal verification. Techniques such as assertion-based verification and state-space exploration can help detect corner cases that are not covered by the normal test cases.
In safety property model checking, states in a model are classified as valid or invalid states. A path to an invalid state signifies a property failure, while the absence of such a path implies that the property holds.
A property indicating eventually a behavior will hold which helps in reducing the time consumed for proving a design.
Advantages of SystemVerilog Assertions in Formal Verification
The use of SVA in formal verification offers several compelling advantages:
1. Writing Formal Properties
SVAs can examine the data path and internal state of the design.. They provide a rich and versatile language for expressing intricate properties, encompassing temporal logic, safety properties, and liveness properties. This enables the precise specification of design behavior.
2. Faster Debugging
Formal properties offer faster debugging time in proving the correctness of reasonable design sizes
In formal verification, there is no particular stimulus driving involved. We write the properties concerning a system or a design defining its behavior in SVA. The Formal tool generates a wide range of random stimuli that prove or falsify the properties.
By writing Formal Properties, The design failure can be easily detected as the assertion failure. The formal tool aids in coverage with the entirety of the state space of a design.
There is more to explore SVA in regards to formal verification. The exploration of in-depth mathematical magic can be explored by joining a VLSI institute like Chipedge where the extensive training is going to make oneself an efficient Verification Engineer.
As the field of VLSI continues to evolve, a VLSI design course plays a crucial role in equipping engineers with the skills and knowledge needed to excel in this domain. SVA is an essential topic that should be included in a VLSI online course to prepare future engineers for the challenges of modern semiconductor design. As VLSI continues to advance, The use of SVA will remain a significant tool in formal verification, ensuring the reliability and correctness of cutting-edge integrated circuits.