20 UVM Verification Interview Questions and Answers

UVM Verification is a popular methodology used in the semiconductor industry to verify the design of integrated circuits. When interviewing for a position in this field, it is important to be prepared to answer questions about your experience and knowledge of UVM Verification. In this article, we review some of the most common UVM Verification questions and provide tips on how to answer them.

UVM Verification Interview Questions and Answers

Here are 20 commonly asked UVM Verification interview questions and answers to prepare you for your interview:

1. What is UVM?

UVM is the Universal Verification Methodology. It is a standard for verification that can be used with any design or verification language.

2. Can you explain the architecture of a UVM testbench?

The architecture of a UVM testbench typically consists of four main components: the environment, the agent, the monitor, and the scorecard. The environment is responsible for initializing the DUT and setting up the testbench. The agent is responsible for driving the stimulus to the DUT. The monitor is responsible for checking the response of the DUT to the stimulus. The scorecard is responsible for keeping track of the results of the verification.

3. How does UVM handle error handling and reporting?

UVM provides a mechanism for handling errors and reporting them back to the user. This is done through the use of the uvm_report_server and the uvm_report_handler. The uvm_report_server is responsible for receiving and storing reports, while the uvm_report_handler is responsible for displaying the reports to the user.

4. What are some common steps involved in creating a UVM based verification environment?

The first step is to create a testbench that instantiates the DUT and the UVM environment. Next, you need to create a UVM agent for each interface on the DUT. Each agent will contain a UVM driver and a UVM monitor. The driver will generate traffic to stimulate the DUT, and the monitor will check the DUT’s response to ensure that it is correct. Finally, you need to create a UVM scorecard to track the progress of the verification and provide a report at the end.

5. Can you explain what a sequence item is in the context of UVM?

A sequence item is an object that represents a specific piece of data that is being passed between two components in a UVM testbench. This could be a single bit, a byte, a word, or even a larger chunk of data. A sequence item has a number of associated fields that describe the data it is carrying, as well as methods that can be used to manipulate that data.

6. What are virtual sequences? When should they be used?

Virtual sequences are a type of UVM test that can be used to verify the functionality of a design. They are used to generate traffic that is directed at the DUT, and can be used to check for proper functionality and response. Virtual sequences should be used when you want to generate traffic that is directed at the DUT, and you want to check for proper functionality and response.

7. What is a factory? Why do you need it when working with UVM?

A factory is a class that is used to create objects in UVM. The factory is used to manage the creation and destruction of objects, and to keep track of all the objects that have been created. This is important in UVM because it allows different parts of the verification environment to communicate with each other and share information.

8. What happens when a uvm_sequence gets aborted or ends normally?

When a uvm_sequence gets aborted, it will stop executing and go back to the beginning. If it ends normally, it will continue to the next sequence in the order.

9. Is there a way to end a sequence prematurely? If yes, then how?

Yes, there is a way to end a sequence prematurely. This can be done by using the uvm_fatal or uvm_stop macros.

10. What’s the difference between an action and a callback in UVM?

An action is a piece of code that is executed in response to a specific event, such as when a transaction is received. A callback is a piece of code that is executed when a certain condition is met, such as when a certain number of transactions have been received.

11. How can you define custom types for use in your env?

You can use the typedef command to create custom types for use in your UVM env. This is useful for creating custom data types that can be used throughout your verification process.

12. Are there any risks associated with using generics in UVM? If yes, then can you list them all?

Yes, there are some risks associated with using generics in UVM. One of the biggest risks is that it can lead to code that is difficult to read and understand. Additionally, it can be easy to make mistakes when using generics, which can lead to verification errors.

13. What is the best way to create unique names for various instances of UVM components?

One way to create unique names for various instances of UVM components is to use the uvm_component_name macro. This macro will automatically generate a unique name for each instance of a component, based on the name of the component and the instance number.

14. What’s the main advantage of using macros in UVM code?

The main advantage of using macros in UVM code is that it allows for a more concise and readable code. By using macros, you can avoid having to write out long lines of code that would be difficult to read and understand.

15. How can you configure multiple agents in UVM?

You can configure multiple agents in UVM by using the uvm_config_db class. This class allows you to store and retrieve configuration information for various UVM components. You can use it to specify the number of agents you want to create, as well as other parameters such as the agent’s name and type.

16. Can you explain what functional coverage analysis is?

Functional coverage is a type of verification that is used to check if the design under test is exercising all of the intended functionality. This can be done by looking at the inputs and outputs of the design and checking to see if all of the possible combinations of inputs and outputs have been covered.

17. What are the advantages and disadvantages of using UVM over SystemVerilog OOPs?

The main advantage of using UVM is that it provides a standard library and methodology for verification. This can be a big advantage when working on large, complex projects with multiple verification engineers, as it helps to ensure that everyone is working in a consistent way. The main disadvantage of UVM is that it can be quite complex and difficult to learn, especially if you are coming from a background of using SystemVerilog OOPs.

18. What is the process followed by a driver to send data to its connected DUT port?

The process followed by a driver to send data to its connected DUT port is as follows:

1. The driver first initializes its data structures.
2. The driver then configures its connected DUT port.
3. The driver then writes the data to be sent to the DUT port.
4. The driver finally waits for the DUT to respond.

19. What happens if you call start() on a sequence that has already been started once before?

If you call start() on a sequence that has already been started once before, then the sequence will restart from the beginning.

20. How do you separate simulation setup from the rest of the test bench code?

By using the UVM configuration database, you can store all of your simulation setup information in a separate file from your test bench code. This makes it easy to change your simulation setup without having to modify your test bench code.