What should you expect in an VLSI interview as a fresher

This post is for everybody who is or was ever interested in working in a electronics core industry, or developing a hardware system. Though my post will be on entering in VLSI industry, more specifically in Digital VLSI Systems.
Well, to be honest it won't be easy. But then congratulations, most difficult tasks are the most rewarding, and I mean it not just in terms of money/salary, but in regards to a competent and challenging task as well.

Well if you are one of the many who is preparing for an entry-level job in VLSI out of a Bachelor's or Master's degree, this post will definitely guide you on how you could keep your preparations more focused.The post is based on my and a few of my colleagues' experiences in VLSI interviews.

You won't get a plethora of interview calls from the industries, so when you fetch one make sure you crack it. Having said that, there are many courses available, which can help you bridge the gap from your Fresher's status to an industry professional. There won't be much difference in the interviews of VLSI institutions or companies. They will test your basic, and how robustly are holding on to your fundamentals.

Here a few topics you cannot miss out while preparing for your interviews:

Number systems and conversion:
Numbers could be given in a number system of any base, even the non-standard ones. You could be asked to find equivalent of a number in another base.

Binary arithmetic:
Addition, subtraction, multiplication, division seeming easier in decimal base, but could be a head spinner with binary numbers.

Arithmetic in other bases:
Same is true for arithmetic computations in other bases.

Floating point representation IEEE standard:
IEEE has standardized floating point number representations. In it's simplest form a fixed-point number could be asked to represent in floating-point and vice versa.

Logic gates and conversion:
Make sure you know truth table, logic symbol, boolean equivalent. This could be very basic. It could be made more challenging by asking you to convert a logic equivalent using other gate. For instance, you could be asked to implement a NAND gate using only EX-OR gates.

Combinational blocks - Adder, Multiplier, Mux, Encoder, Decoder:
You could be asked for a structural equivalent of basic combinational blocks using gates. So be particularly well prepared for such questions, so that you don't fumble deriving boolean expression, and then deriving the circuit for the same. This is difficult in front of the interviewer (based on personal experience).

Sequential basics:
Make sure you're thorough with all the SR, JK, D, T flip-flops and latches, including their logic/boolean representation, circuit diagram, state table. Conversion of logic equivalent of one flop using other flop. You surely cannot afford to miss on difference between flip-flops and latches.

Setup/hold concepts:
If you answer all above questions correctly, you've sure signed up for questions on these topics, and trust me it could get real nasty. Keep your fundamentals clean. For details on above topic.
If you answer above question well, you could also be interviewed on metastability and race-around conditions. For details.

Finite State Machines, pattern detectors:
Starting with difference on Mealy and Moore machines, you could be asked to design an FSM. Especilally, designing FSMs for pattern detectors (over-lapping and non-over-lapping). The difficult it seems, the easier it is, just make sure you have your concepts prepared.

Transistors basics:
This could be rarely asked in an Digital Logic Design interview, though could be potential question and a decider one in Physical Design or Analog Design interview. Stick well to the concepts.

Micro Processor basics:
This could also be inspected. Make sure you know the basics of a processor functioning, the basic blocks (ALU, Cache, Data Bus, Control decoder, instruction and data memmory, RAM).

Verilog basics:
This could be inspected as well if you've signed up for a job interview especially the ones which do not involve any prior company training in the domain. You have to know different styles of coding in Verilog, datatypes, Testbench, RTL Design.

That was all I knew for my own as well through a few of my colleagues experiences. Do let me know in the comment section, if you have witnessed any other question's type, or if you know of any other questions which I might have missed above, I will surely add to the content.

All the best!

Comments

  1. hello

    I have a one question i.e verilog is which level of language high level or low level?

    ReplyDelete
    Replies
    1. Hi,

      In a software development environment, a programmer codes in high level language(C++, Java...) and uses a compiler to interpret it to a low level programming language. Taking that analogy to Hardware Development environment, a designer will define functionality (behavioral style) in Verilog or VHDL and use a Synthesis tool to map it to a netlist (Technology dependent or independent). But a designer can also define functionality directly using HDL(Verilog) in netlist (structural style), again, technology dependent or independent.
      That is my understanding, not a universal answer, may be because I have never looked at Verilog as a programming langauge, but always as a Hardware Definition Language.
      Let me know if that was helpful or did it confuse you even more!

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