36 Questions to Ask About VLSI (With Sample Responses)
When millions of MOS transistors are put on a single chip, like a microchip, to make a circuit, this is called very large scale integration (VLSI). You need to know how this process works if you want to work in computer engineering. To get ready for an interview about this subject, you can do research and practise with common interview questions. This article looks at 11 VLSI interview questions and how to answer them, as well as 25 more questions that you can use to prepare for your next interview.36 Questions to Ask About VLSI
VLSI interview questions and sample responses
Here are 11 of the most common VLSI interview questions, along with examples of how to answer them:
1. What do you think VLSI, which stands for “very large scale integration,” means?
This question sets the tone for the rest of the interview, so they may ask it first and expect you to know the answer. Make sure you know what VLSI stands for in general so you can answer with confidence.
Example: “Most of the time, VLSI is just a way to make integrated circuits by putting millions of MOS transistors on a single chip. Without these ICs, it would not be possible to make integrated circuit microchips. The microchips can then be used in a wide range of tools, like semiconductors and telecommunications.”
2. What is boolean logic? How do I use it?
Boolean logic is a key part of making VLSI and microchips, so this question is likely to come up. Since it involves Boolean algebra, you could also say something about that in your answer to show how much you know.
Example: “The idea behind Boolean algebra is that every value is either true or false. Simple programmes that compare things can use Boolean logic. You can make better decisions based on whether a value is true or false.”
3. What is Verilog, and how is it different from other common programming languages?
You need to know how to use other programming languages to answer this question, so make sure you know a few so you can tell them apart.
Example: “Verilog is a language that is used to talk about hardware. It is used to talk about electronic circuits and systems. Basically, you put the parts of the circuit together inside a module that has statements for structure and behaviour. It is different in a number of ways from other programming languages. First of all, it has more than one thread and uses simulation time, which none of the others do. It also has basic information about circuits, like what primitive gates are.”
In VLSI, what is a depletion region?
Make sure you understand this idea so you can answer quickly and with confidence. Try to explain as much as you can about the depletion region.
Example: “A positive voltage along the gates causes the depletion region by moving a positive charge away from the area under the channel region where the substrate is. When the holes are pushed down into the substrate, this depletion area is made. There are no more cell phone service providers in this area or zone. The only things left are acceptor impurities and ionised donors.”
5. What is a procedural block, and what are the two types in Verilog?
You can give more information about the two different kinds for this question. If you can’t remember both, try to name at least one of them.
Example: “In Verilog, a procedural block is a loop that runs the same set of statements automatically over and over again. You use procedural blocks to keep doing small tasks that don’t change the design. The two kinds are first and always.”
6. What is a skew, and how is it used in VLSI?
Find out what skew is and keep it in mind so you can give a full answer in a short amount of time. Give a short description of each type to show how well you know it.
Example: “In VLSI, a skew is a part that makes it easier to understand how the process works and cuts down on the number of delays. There are many kinds of skews, but the three most important ones are local skew, global skew, and useful skew.”
7. What are some ways that setup and hold is broken?
Explain what a setup and hold violation is and why it’s important. You could also say a few words about some of the broken rules.
Example: “Setup and hold violations are when work processes in design don’t change at the right time. For the state machine to work as it was meant to, the data has to move from one flop to the next at the right time. When these set-ups and hold paths don’t work, the design is broken.”
8.What do you do to fix setup and hold violations in VLSI?
You should look up the steps and memorise them so you can answer this question with confidence and tact. You need to know the four most important steps. Try to remember at least two or three steps if you can’t remember all of them.
Example: “There are many ways to fix set up and hold violations. I’ve seen that the logic between each flip can be improved and then rearranged. This makes the logic work, so the problem is solved. You can also change the clock’s network to make it pick up flip-flop actions faster or slower.”
What does it mean to break an antenna, and how can you stop it?
When you answer this question, be clear and direct. There are many ways to stop this from happening, so try to name at least two of them to show how much you know.
Example: “During plasma etching, an antenna violation can happen when charges from one metal strip to another build up in one area. This happens because the charges add up based on how long the strip is, so a longer strip can add up to more charges. The problem can be fixed by moving the metal. You could also prevent this from happening by putting reverse diodes at the gates of the circuit.”
What are some of the differences between a CMOS chip and a TTL chip?
There are many things that are not the same. Try to talk about at least two main things that are different.
Example: “How they work is the main difference between them. Most cell phone chips are CMOS chips, while most computer chips are TTL chips. Also, CMOS chips have FETs, while TTL chips have BJTs. Another difference is that TTL chips use a lot of power and energy even when they are not doing anything. A CMOS chip uses much less power than an NMOS chip.”
11. What are integration circuits, and how many generations of them have there been?
If you understand this idea and have time, you can say more about each of the four generations to show how they are different. If you talk about each one, explain what it is in a few words.
Example: “A group of electronic circuits that are all put on a small, flat silicon semiconductor is an integration circuit. Integration circuits come in four different sizes: small, medium, large, and very large.”
25 additional VLSI interview questions
Check out this list of 25 more VLSI interview questions that the hiring manager may ask you:
- How do you keep VLSI from going into metastability?
- What is the purpose of a multiplexer?
- What is a rectifier that is controlled by silicon?
- What is different about a CMOS chip from a TTL chip?
- In VLSI circuits, MOSFETs are used instead of BJTs for a few reasons.
- What are the three main ways a MOSFET can do its job?
- What gates use Boolean logic?
- Explain what it means that “the channel is closed off.”
- What does it mean to change a channel’s length?
- What are DCMs and how do you use them?
- How does a defparam work, and what is it?
- How many different types of Cmos processes are there?
- How many transistors does a static RAM use?
- What does it mean to modulate the length of a channel?
- Tell me about tie-high and tie-low cells.
- In the synthesis phase, what are some of the different design constraints?
- How does Moore’s law work?
- What is PLA? What is PAL? What do they have in common?
- Tell me the rules for making technology that is based on VLSI.
- How is the CMOS logic different from the pass transistor?
- What’s the difference between ROBDD and OBDD?
- What is a soft error, and how can you fix it?
- Describe some of the issues with the DSM
- What is MTBF in VLSI?
- What are the biggest differences between a Mealy machine model and a Moore machine model?
