Facing Interview For Fresher

After Post-COVID situation we are gradually approaching the normal life. Although many companies are following hybrid model of work-from-home and work-from-office , hiring has started. So we decided to discuss about general interview structure and essential topics a vlsi fresher must know.

 Any fresher usually face there types of screening.

1. Written Test :

In this article episode we will limit our discussion within core technical part. In written question paper you will face aptitude questions and technical questions. Technical questions will cover both electronics and programming. 

2. Face-to-face/ f2f Round  :

If you clear the written paper you will be selected for multiple round of f2f interviews. In f2f mostly technical questions are asked. Here also you will face questions from core electronics part and programming part.

3. HR round :

In HR round the person on the other side of the table will try to understand you. They have seen your technical capabilities in technical interview and now want to understand you as a team player. Its important for the team and the unit you are joining. 

For HR preparation there are tons of free material in internet. Search them, read them, watch videos. Talk to your seniors.

Preparation For Technical Interview :

Now lets see what are the topics you need to know for technical interview : 

For core electronics part first comes analog electronics.

 1.  Analog electronics :

• In analog electronics you need to know basic structure, functioning, circuit behavior i.e. characteristics of different semiconductor devices  like  diode, zener diode, BJT, MOSFET etc. Basics means structure, how current  flows, how the device works.
• Their characteristics, Different configutration of BJT and MOSFET is equally important. Circuit configuration and I-V plot. You might have to explain it on pen and paper. 
• OP-AMP is very important. Uses of OP-AMP is very common in interview. They might ask you todraw the ckt diagram and explain the operation of the ckt with input and output waveform. 
•  All kinds of active and passive filters, their charcterinstics, ckt diagram, wave form are equally important.
• The  PLL ckt is used as a clock generator in vlsi chips. Hence the PLL ckt and its operation has grave importance in VLSI chips. So you must be  through in knowledge of design of a PLL upto the tansistor level and you must understand its operation from the transistor perpective.

2. Digital electronics: 

• Starting from Number Systems, Boolean algebra, Logic gates, Combinational circuits and Sequential circuits, MUX, Decoder  , latch, Flip flops,  State Machines, all types of memories ADC and DAC and logic families like  ECL,TTL etc are important. Memory includes RAM,  ROM, SRAM, DRAM, EPROM, Non-volatile memory, Cache memory etc. You cannot afford to skip any topic from digital electronics. So be thorough in your preparation. In any of the topic you might need to draw the diagram and explain.
• In semiconductor memories, you must focus on the circuit operation, how a purely analog circuit helps to preserve an array of digital beats.You must also understand similarities and dissimilarities among RAM, ROM, EPROM,Non Volatile memories etc.
• In non-volatile memories you must also focus on the architectural difference between NAND, AND, NOR arrangements of NVM. You must also know why these arrangements are compared to the NAND and NOR architectures.

3.  VLSI fabrication process

• Crystal growth , Wafer preparation , Oxidation , Diffusion , Ion implantation , Lithography, Epitaxy , Etching, Poly-silicon, Dielectric film deposition, Metalization, Yield and reliability these are the steps which are used to fabricate a chip. Hence you need to cover all these topics. 
• Learn to draw stick diagram of couple of popular circuits you find in your text book. These stick diagrams are very important if you are interviewed for opening in physical design or layout design team.

4. Overview of VLSI design flow :

Learn the sequential steps of VLSI design flow. Since you are a fresher deep knowledge is not expected however fundamentals must be thoroughly covered .You must know significance of each and every step. Your understanding must be very clear about how a step is connected to its previous and next steps. Try to know the name of some commercial tools used for each step.

5. CMOS circuits and logic design:

In this section questions are asked related to NMOS and PMOS operation and CMOS inverter, Noise margin and CMOS operation . Understand the circuit and  prepare to explain it with input and output waveform. You must also go thorough in the designs of NAND, NOR, AND etc the basic logic gates using the CMOS transistor circuit. Those who are interesting in digital designing may venture out in a bit of more complex digital circuit  like MUX, DECODER, ENCODER using the CMOS transsistor architechture.

For each interview , while you are preparing,  if you have  job role and required skill set study it carefully. Follow your own gut feeling in addition to the help provided in the video :

6. Programming Skill : 

From Programming or coding part you need to know

• C/C++ and data structure.
• Scripting language like -PERL, Python,  TCL, Shell scripting
• PERL, Pytthon, TCL and Shell are most frequently used in VLSI flow. So try to learn all of them. Parsing, flow automation,  report generation, data extracting all are done by scripting languages. While working with EDA tools , TCL is most important. All the tool command written in TCL. You can write wrapper in TCL to run a tool. 
• Basic Linux command- basic linux command you need to know for day to day work.

Detailed and in-depth series on PERL, TCL, BASH scripting and LINUX are available on our YOUTUBE channel. 

Series on PERL  : 

Series on TCL  : 

Series on BASH : 

Well these are the topics you need to know for your interview. Once a company hire you, usually , they will train you for specific domain. Most companies have well structured training module. So keep learning, and keep enjoying the process. 

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