17 FPGA Engineer Interview Questions and Answers

FPGA engineers design and develop the hardware that makes our digital lives possible. From the chips in our phones to the massive data centers that run the internet, FPGA engineers are responsible for the circuitry that makes all our devices work.

If you’re looking to join this in-demand field, you’ll need to be able to answer some tough questions during your interview. To help you get started, we’ve compiled a list of the most common FPGA engineer interview questions and answers.

Are you familiar with the Verilog programming language?

Verilog is a programming language used to create FPGA designs. The interviewer may ask this question to see if you have experience with the Verilog language and how it relates to FPGAs. In your answer, try to explain what Verilog is and why it’s important for FPGA engineers to know how to use it.

Example: “Yes, I am familiar with the Verilog programming language. When I was in school, my professor taught us about Verilog because it’s one of the most common languages used by FPGA engineers. It’s helpful to be able to understand the Verilog language because it allows me to read other engineers’ code and learn from their work.”

What are the pros and cons of using a hardware description language to program an FPGA?

This question allows you to demonstrate your knowledge of the tools and techniques used in FPGA programming. Your answer should include a list of pros and cons that show you understand how HDLs work with FPGAs.

Example: “HDLs are useful because they allow engineers to use a hardware-independent language to program an FPGA, which means I can create one design and then compile it into different types of hardware. However, this is also a disadvantage because if there’s a problem with the code, I have to fix it on each type of hardware separately. Another disadvantage is that using HDLs requires more time and money than other methods.”

How would you go about debugging a design that isn’t working properly on an FPGA?

Debugging is a skill that many employers look for in an FPGA engineer. Debugging involves finding the cause of a problem and fixing it, which can be very important when working on projects with tight deadlines. Your answer should show your interviewer that you have the skills to debug designs effectively.

Example: “I would first check if there are any errors in the code I wrote. If not, then I would go through all the hardware components of the design to see if they’re functioning properly. For example, I might need to replace some faulty memory or reconfigure the routing network. Once I fix these issues, I will run my test again to make sure everything works as expected.”

What is the difference between a gate-level implementation and a behavioral implementation of an FPGA design?

This question allows you to demonstrate your knowledge of the two main types of FPGA design. Your answer should include a clear definition for each type and how they differ from one another.

Example: “Gate-level implementation is when you use logic gates to create an FPGA design. This process involves creating a circuit that uses AND, OR and NOT gates to implement a specific function. A behavioral implementation is when you describe the behavior of a system in VHDL or Verilog code. It’s important to note that this method requires more time and effort than gate-level implementation.”

Provide an example of a time-critical application where an FPGA would be more appropriate than an ASIC.

This question allows you to demonstrate your knowledge of the differences between FPGAs and ASICs. You can use an example from a previous job or describe how you would choose between the two technologies in a given situation.

Example: “In my last role, I was tasked with creating a new chip that could process data at 100 gigabytes per second. The company wanted to create a single-chip solution that could be used for multiple applications. We decided to build the system using an FPGA because it allowed us to change the hardware as needed without having to redesign the entire chip. This saved time and money while still allowing us to meet our client’s needs.”

If you were to design an FPGA for a specific application, what would be the most important factors to consider?

This question is a great way to assess the candidate’s knowledge of FPGA design and how they would apply it in their work. When answering this question, you can explain what factors are important for designing an FPGA and why each factor is important.

Example: “The most important thing I would consider when designing an FPGA for a specific application is the power consumption. This is because power consumption directly affects the cost of using the device. If the power consumption is too high, then the device will be more expensive than other options that have lower power consumption. Another important factor is the size of the FPGA. The smaller the FPGA, the less space it takes up on a circuit board.”

What would you do if you were working on a project and realized that the FPGA you were using was not capable of performing at the level required?

This question can allow the interviewer to assess your problem-solving skills and ability to adapt. Your answer should include a specific example of how you would approach this situation, including what steps you would take to resolve it.

Example: “If I was working on a project that required high performance but my FPGA wasn’t capable of performing at that level, I would first try to find out why it couldn’t perform as expected. If there were no issues with the design or implementation, then I would look into other options for increasing its performance. One option could be using an FPGA that is more powerful than the one I’m currently using.”

How well do you understand the limitations of FPGAs? Can you provide an example of a situation where these limitations would become apparent?

The interviewer may ask you this question to assess your knowledge of the limitations of FPGAs and how you would respond to them. Your answer should include a clear understanding of the limitations of FPGA technology, as well as an example of when these limitations became apparent in your previous role.

Example: “FPGAs are great for implementing complex logic functions because they can be reconfigured on-the-fly. However, there are some limitations that I have encountered while working with FPGAs. For instance, if I need to change the configuration of an FPGA frequently, it will require more power than other solutions such as ASICs. Also, FPGAs cannot be used to create large arrays of memory or perform mathematical operations.”

Do you have experience working with FPGA clusters? If so, what is the largest cluster size you have worked with?

FPGA clusters are groups of FPGAs that work together to perform a single task. This question helps the interviewer determine your experience with working in teams and how you might fit into their organization. In your answer, explain what it means to have an FPGA cluster and give examples of when you used one in previous roles.

Example: “In my last role as an FPGA engineer, I worked on several projects where we needed to use multiple FPGA clusters. The largest cluster size I’ve ever worked with was 100 FPGAs. However, I also had experience working with smaller clusters of five or six FPGAs.”

When would you use a soft core versus a hard core?

This question can help the interviewer understand your knowledge of FPGA technology and how you apply it to a project. Use examples from past projects or experiences to show that you know when soft core is more effective than hard core.

Example: “Soft core is better for applications where I need to change the logic frequently, while hard core is better for applications with less frequent changes in logic. For example, at my last job, we used soft core for our application because we needed to make changes to the logic every few hours. However, we used hard core for our other applications because they didn’t require as many changes.”

We want to allow our engineers to customize the functionality of our FPGAs. What design methodology would you recommend for us?

This question allows you to demonstrate your knowledge of FPGA design and the different methods available. You can discuss a specific methodology or provide an example of when you used one in your previous role.

Example: “I would recommend using hierarchical methodologies, which allow engineers to create sub-blocks within their designs. This gives them more control over how they customize functionality. In my last position, I was tasked with creating a new system that could handle large amounts of data. Using this method, I created multiple layers of sub-blocks within the main block, allowing me to adjust the size of each layer as needed.”

Describe your process for handling design reuse in FPGA projects.

This question allows you to demonstrate your problem-solving skills and ability to apply past experiences to future projects. Your answer should include a specific example of how you handled design reuse in the past, along with the steps you took to ensure successful implementation.

Example: “In my last role as an FPGA engineer, I was tasked with creating a new circuit board for a client’s product line. The company wanted to use the same circuit board for multiple products, which required me to create a reusable design that could be applied to different devices without any issues. To do this, I first created a schematic diagram of the circuit board, then used VHDL code to program the FPGA chip. After testing the functionality of the circuit board, I implemented it into the client’s product line.”

What makes FPGAs so attractive for applications that require high performance?

This question is an opportunity to show your knowledge of FPGA technology and how it can be applied in a variety of industries. Your answer should include examples of the benefits of using FPGAs over other types of hardware, such as ASICs or CPUs.

Example: “FPGAs are attractive for applications that require high performance because they offer flexibility and reconfigurability. This means I can change the circuit design on-the-fly without having to replace the entire chip. In my last role, we used this feature to create a new application within 24 hours. The ability to quickly adapt to changing requirements makes FPGAs ideal for many different industries.”

Which FPGA development tools have you used in the past and which ones do you prefer?

This question helps the interviewer determine your experience level with FPGA development tools. It also allows them to see if you have a preference for any specific tool and why. When answering this question, it can be helpful to list all of the tools you’ve used in the past and explain what makes each one unique or beneficial.

Example: “I’ve worked with Xilinx Vivado Design Suite, Altera Quartus II Software and ISE WebPACK from Intel. I prefer working with Vivado because it’s easy to use and has many features that make my job easier. For example, I like how it has built-in simulation and debugging tools that allow me to test out different designs before implementing them into an actual product.”

What do you think is the most important aspect of FPGA verification?

This question is your opportunity to show the interviewer that you understand how important verification is in FPGA engineering. Your answer should include a brief explanation of what you think is most important about this process and why it’s so vital to the success of an FPGA project.

Example: “I believe the most important aspect of FPGA verification is making sure all of the code is correct before implementation. If there are any errors or bugs in the code, they can cause problems with the functionality of the circuit board. I always make sure to thoroughly check my work for accuracy and eliminate any issues prior to implementing the code into the FPGA.”

How often do you perform FPGA verification and what is your process for doing so?

This question is an opportunity to show your interviewer that you have the skills and knowledge necessary to perform this important task. Your answer should include a description of what verification is, how often you do it and what tools you use for the process.

Example: “Verification is when I check my work to ensure that all of the FPGA’s components are functioning properly. I typically perform verification after completing each major step in the design process. For example, I would verify my initial schematic before moving on to implementation and then again before creating any bitstreams.”

There is a bug in your FPGA code and you are running out of time to fix it before the product goes to market. What would you do?

This question is a great way to test your problem-solving skills and ability to work under pressure. Your answer should show that you can prioritize tasks, manage time effectively and communicate clearly with others.

Example: “If I am running out of time before the product goes to market, I would first try to fix the bug myself. If this proves too difficult, I would ask my team members for help. We would then decide on who will do what based on our individual strengths. For example, if someone has more experience in debugging FPGA code than me, they could take over the task while I focus on other important aspects of the project.”