Verilog Interview Questions and Answers, Verilog Interview Questions and Answers Freshers, Verilog Interview Questions and Answers, Verilog Interview Questions
Before getting on to the Verilog interview questions, the student must know that the Verilog is a continuously varying field which needs the students as well as professionals to upgrade their skills with the new features and knowledge, to get fit for the jobs associated with Verilog. This post related to Verilog Interview Questions and Answers, Verilog Interview Questions and Answers Freshers, Verilog Interview Questions and Answers, Verilog Interview Questions will help you let out find all the solutions that are frequently asked in you upcoming Verilog interview.
Over thousands of vacancies available for the Verilog developers, experts must be acquaintance with all the component of Verilog technologies. This is necessary for the students in order to have in-depth knowledge of the subject so that they can have best employment opportunities in the future. Knowing every little detail about Verilog is the best approach to solve the problems linked with problem.
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Hence, if you are looking for boosting up your profile and securing your future, Verilog will help you in reaching the zenith of your career. Apart from this, you would also have a lot of opportunities as a fresher.
These questions alone are omnipotent. Read and re-read the questions and their solutions to get accustomed to what you will be asked in the interview. These Verilog interview questions and answers will also help you on your way to mastering the skills and will take you to the giant world where worldwide and local businesses, huge or medium, are picking up the best and quality Verilog professionals.
This ultimate list of best Verilog interview questions will ride you through the quick knowledge of the subject and topics like Verilog Architecture, ASIC Verification Methodologies, Directed Vs random. This Verilog interview questions and answers can be your next gateway to your next job as a Verilog expert.
These are very Basic Verilog Interview Questions and Answers for freshers and experienced both.
Q1: Difference Between Task And Function?
- A function is unable to enable a task however functions can enable other functions.
- A function will carry out its required duty in zero simulation time. ( The program time will not be incremented during the function routine)
- Within a function, no event, delay or timing control statements are permitted
- In the invocation of a function their must be at least one argument to be passed.
- Functions will only return a single value and can not use either output or inout statements.
- Tasks are capable of enabling a function as well as enabling other versions of a Task
- Tasks also run with a zero simulation however they can if required be executed in a non zero simulation time.
- Tasks are allowed to contain any of these statements.
- A task is allowed to use zero or more arguments which are of type output, input or inout.
- A Task is unable to return a value but has the facility to pass multiple values via the output and inout statements .
Q2: Difference Between $monitor,$display & $strobe?
A2: These commands have the same syntax, and display text on the screen during simulation. They are much less convenient than waveform display tools like cwaves?. $display and $strobe display once every time they are executed, whereas $monitor displays every time one of its parameters changes.
The difference between $display and $strobe is that $strobe displays the parameters at the very end of the current simulation time unit rather than exactly where it is executed. The format string is like that in C/C++, and may contain format characters. Format characters include %d (decimal), %h (hexadecimal), %b (binary), %c (character), %s (string) and %t (time), %m (hierarchy level). %5d, %5b etc. would give exactly 5 spaces for the number instead of the space needed. Append b, h, o to the task name to change default format to binary, octal or hexadecimal.
$display (“format_string”, par_1, par_2, … );
$strobe (“format_string”, par_1, par_2, … );
$monitor (“format_string”, par_1, par_2, … );
Q3: Tell Me How Blocking And Non Blocking Statements Get Executed?
A3: Execution of blocking assignments can be viewed as a one-step process:
1. Evaluate the RHS (right-hand side equation) and update the LHS (left-hand side expression) of the blocking assignment without interruption from any other Verilog statement. A blocking assignment “blocks” trailing assignments in the same always block from occurring until after the current assignment has been completed
Execution of nonblocking assignments can be viewed as a two-step process:
- Evaluate the RHS of nonblocking statements at the beginning of the time step.
- Update the LHS of nonblocking statements at the end of the time step.
Q4: In A Pure Combinational Circuit Is It Necessary To Mention All The Inputs In Sensitivity Disk? If Yes, Why?
A4: Yes in a pure combinational circuit is it necessary to mention all the inputs in sensitivity disk other wise it will result in pre and post synthesis mismatch.
Q5: There Is A Triangle And On It There Are 3 Ants One On Each Corner And Are Free To Move Along Sides Of Triangle What Is Probability That They Will Collide?
A5: Ants can move only along edges of triangle in either of direction, let’s say one is represented by 1 and another by 0, since there are 3 sides eight combinations are possible, when all ants are going in same direction they won’t collide that is 111 or 000 so probability of not collision is 2/8=1/4 or collision probability is 6/8=3/4
Q6: What Is The Difference Between The Following Two Lines Of Verilog Code?
A6: #5 a = b;
a = #5 b;
#5 a = b;
Wait five time units before doing the action for “a = b;”.
a = #5 b; The value of b is calculated and stored in an internal temp register,After five time units, assign this stored value to a.
Q7: How To Generate Sine Wav Using Verilog Coding Style?
A7: The easiest and efficient way to generate sine wave is using CORDIC Algorithm.
Q8: Why Is It That “if (2’b01 & 2’b10)…” Doesn’t Run The True Case?
A8: This is a popular coding error. You used the bit wise AND operator (&) where you meant to use the logical AND operator (&&).
Q9: Variable and signal which will be Updated first?
Q10: What is sensitivity list?
A10: The sensitivity list indicates that when a change occurs to any one of elements in the list change, begin…end statementinside that always block will get executed
Q11: Tell me how blocking and non blocking statements get executed?
A11: Execution of blocking assignments can be viewed as a one-step process:1. Evaluate the RHS (right-hand side equation) and update the LHS (left-hand side expression) of the blocking assignment without interruption from any other Verilog statement. A blocking assignment “blocks” trailing assignments in the same always block from occurring until after the current assignment has been completed Execution of non blocking assignments can be viewed as a two-step process:1. Evaluate the RHS of non blocking statements at the beginning of the time step. 2. Update the LHS of non blocking statements at the end of the time step
Q12: How to write FSM in verilog?
A12: There r mainly 4 ways 2 write fsm code
1) Using 1 process where all input decoder, present state, and output decoder r combine in one process.
2) Using 2 process where all comb ckt and sequential ckt separated in different process
3) Using 2 process where input decoder and persent state r combine and output decoder seperated in other process
4) Using 3 process where all three, input decoder, present state and output decoder r separated in 3 process.
Q13: How to generate sine wav using verilog coding style?
A13: The easiest and efficient way to generate sine wave is using CORDIC Algorithm.
Q14: What is the difference between wire and reg?
A14: Net types: (wire, tri)Physical connection between structural elements. Value assigned by a continuous assignment or agate output. Register type: (reg, integer, time, real, real time) represents abstract data storage element. Assigned values only within an always statement or an initial statement. The main difference between wire and reg is wire cannot hold(store) the value when there no connection between a and b like a->b, if there is no connection in a and b, wire loose value. But reg can hold the value even if there in no connection. Default values: wire is Z, reg is x.
Q15: What is Constrained-Random Verification ?
As ASIC and system-on-chip (SoC) designs continue to increase in size and complexity, there is an equal or greater increase in the size of the verification effort required to achieve functional coverage goals. This has created a trend in RTL verification techniques to employ constrained-random verification, which shifts the emphasis from hand-authored tests to utilization of compute resources. With the corresponding emergence of faster, more complex bus standards to handle the massive volume of data traffic there has also been a renewed significance for verification IP to speed the time taken to develop advanced test bench environments that include randomization of bus traffic.
Building a directed verification environment with a comprehensive set of directed tests is extremely time-consuming and difficult. Since directed tests only cover conditions that have been anticipated by the verification team, they do a poor job of covering corner cases. This can lead to costly re-spins or, worse still, missed market windows.
Q16: What do we mean by continuous assignment ?
A16: Continuous assignment is used to drive values to net. Left hand side can be scalar or vector net or concatenation of both while right hand side can be scalar or vector net or register or concatenation of both.
Q17: What is the difference between wire and reg?
A17: Table: Difference between Wire and reg
|Assumes Value||Holds Value|
|wire needs drivers to get output values||reg does not need driver|
|wire elements can only be used
to model combinational logic
|reg can be used for combinational as
well as sequential logic
|wire can be used as the left hand
side of an assign statement
|reg cannot be used on the left-hand
side of an assign statement
Q18: What is the difference between $monitor and $display.
A18: $monitor and $display both system functions and are both used to see the testbench results.
|Monitors change in the value of signal.
Signal can be variable, strings or expression.
|Displays the value of signal.|
|Can be invoked once||Can be invoked more than once.|
Q19: What is the difference between == and === operator?
A19: Output of == can be 0,1,X while output of === is always 0 or1.
== doesn’t compare X and if at least one bit is X output will be X.=== compare X bits and output is always 0 or 1 accordingly.
Q20: What is duty cycle?
A20: Duty Cycle is the fraction of time the signal is high or low. It represents on time of a signal. It can be represented by D=T/P where Dis the duty cycle,T is the time signal is active and P is the total time period of signal.
Q21: What is logic synthesis?
A21: Logic synthesis is the mechanism to convert RTL description in terms of gate level representation. The main concern in logic synthesis are fanin, fanout etc. It can be technology dependent or technology independent. Logic synthesis tools are present for this purpose.
Verilog Conclusion Interview FAQs
We know the list of Verilog Interview Questions and Answers, Verilog Interview Questions and Answers Freshers, Verilog Interview Questions and Answers, Verilog Interview Questions is overwhelming but the advantages of reading all the questions will maximize your potential and help you crack the interview. The surprising fact is that this Verilog interview questions and answers post covers all the basic of the Verilog technology and you have to check out the FAQs of different components of Verilog too.
However, you will be asked with the questions in the interview related to the above mentioned questions. Preparing and understanding all the concept of Verilog technology will help you strengthen the other little information around the topic.
After preparing these interview questions, we recommend you to go for a mock interview before facing the real one. You can take the help of your friend or a Verilog expert to find the loop holes in your skills and knowledge. Moreover, this will also allow you in practicing and improving the communication skill which plays a vital role in getting placed and grabbing high salaries.
Remember, in the interview, the company or the business or you can say the examiner often checks your basic knowledge of the subject. If your basics is covered and strengthened, you can have the job of your dream. The industry experts understand that if the foundation of the student is already made up, it is easy for the company to educate the employ towards advance skills. If there are no basics, there is no meaning of having learnt the subject.
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We hope that you enjoyed reading Verilog Interview Questions and Answers, Verilog Interview Questions and Answers Freshers, Verilog Interview Questions and Answers, Verilog Interview Questions and all the FAQs associated with the interview. Do not forget to revise all the Verilog interview questions and answers before going for the Verilog interview. In addition to this, if you’ve any doubt or query associated with Verilog, you can contact us anytime. We will be happy to help you out at our earliest convenience. At last, we wish you all the best for your upcoming interview on Verilog Technology.