Design verification engineer Interview Questions | Glassdoor

# Design verification engineer Interview Questions

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### Digital Design/Verification Engineer at SerialTek was asked...

Mar 16, 2011
 Create a 8 input AND gate using 3 4:1 muxes8 AnswersWithout an enable bit on at least one of the mux's the maximum inputs would be 7.Not so. You only need 2 4:1 muxes. Have the output of the first be the select to the second. 8 input and gate.tie 3 0's to the three inputs of initial 2 4x1 mux, the 3rd input be an actual input, 2 sel be 2 inputs. feed the output of the results of the two muxes as sel to the 3rd mux and tie the last inputs to actual inputs and top two inputs to 0's.Show More ResponsesI can only make it 7 bits with that explenation.I don't see it being possible with three standard 4-1 muxes... Using 4, this question is straight forward... The two selects of each mux are your 8 inputs... tie out put of each mux to the (11) case input to the mux.We need 3 4:1 MUX and a And gate. Are we allowed to use 'and' gate?A to H are the 8 inputs. For the first 2 muxes we can have GH as select bits with all their inputs tied to 0. Connect output of these muxes to the first 2 input lines of third mux. Tie the third input to 0. Now we care only about the 4th input line when EH are both 1s. We can derive an expression and connect it to the 4th input line of third mux. job done.mux1: (0,1,2)==0 and (3)=C with sel: AB ====OUT1==ABC mux2: (0,1,2)==0 and (3)=D with sel: EF ====OUT1==DEF short ABC and DEF as---if any one of them is 0---it will be zero----if both of them are 1---it will be one mux3: (0,1,2)==0 and (3)..shorted out1 and out2 with sel:GH===out:ABCDEFGH

### Design Verification & Test Engineer at Marvell Semiconductor was asked...

Sep 20, 2010
 You have seven stones and a weighing scale. Six of the stones are equal in weight and one is lighter. How will you figure out which one is lighter ? Minimum tries required to do so ? 5 AnswersTrail 1: At random weigh two stones vs. two stones (3 sitting on the side) A: Of the 4 on the scales if one side weighs more then the other then weigh one on each side (since one of them must be heavier) B. If the 2 vs 2 are equal then at random weigh 2 (one on each side) of the three left on the side. If they are the same then the 3rd one that never got weighed is the heaviest. Simple case of process of elimination by grouping (Divide and Test)I would first weigh in one stone, say stone 1, and assume the weight is say 2 lbs(try 1). Then separate the 6 remaining stones into 2 piles, 2,3,4 and 5,6,7. Weigh in either 2,3,4 or 5,6,7, it doesn't matter. Say 2,3,4, if the sum of these 3 is 6 then the lighter stone has to be in the 5,6,7(try 2). Weigh in 5,6, if the sum of the two is 4 then the lighter is stone 7(try3). If sum is less than 4 then weigh in either 5 or 6 to find out. So, the maximum number of tries is 4 and least is 3.Needs two weighing at most: 1. Put {1, 2, 3} on LHS and {4, 5, 6} on RHS. 2. If LHS and RHS are equal 7 is the lighter one. else discard heavier of previously weighed group. Now we have a group 3 stones left. Lets call them A, B, C. 3. Put A on LHS and B on RHS. 4. If LHS and RHS are equal C is the lighter one. else lighter or LHS or RHS is the lighter one. Voila!Show More ResponsesTwo tries. 1st try: 3 : 3, 7th is fake if equal; otherwise, 2nd try: 1:1 picked from the light triple in 1st try. the lighter one is fake if any, the third one fake otherwise.If the stones are made of the same material... they likely have the same density... therefor whichever one looks the smallest, will weigh the least... there... 1 step... just look for the one that is the smallest.

### Senior ASIC Design Verification Engineer at AMD was asked...

Jun 20, 2014
 (Unexpected) What the types of caches?3 AnswersL1, L2 and L3 cachestwo types: fully associative cache and N-way associative cache1. Fully Associative. 2. Direct Mapped. 3. Set Associative

### QCT-Digital Design Verification Engineer at Qualcomm was asked...

Mar 7, 2012
 Given integers from 0-100 stored in an array of size 100 how will you find the missing number? Numbers are randomly entered in the array. 2 Answers0-100 have constant addition. add the numbers in the array and subtract it from the constant sum.Assuming that a number only appears once, find the sum and subtract from the total possible value (1+2+3+....+100) and subtract to find the missing number. But it would be smart to ask if a number can appear multiple times or not since that may increase or decrease the complexity of the problem, but shows that you're really thinking about all the problem parameters.

### Design Verification Engineer at Marvell Semiconductor was asked...

Jul 12, 2012
 1 is heavier than the other 5 marbles among 6 mables . given a weight to find the heavier one.2 AnswersThis should be done in 2 iterations...keep 3 in each hand...higher weight indicates the heavier marble is in that set...now with 3 marbles select 2...if weights are equal then the marble kept aside is the heavier one..2 iterations. Take any 4 out of 6 and weigh 2 vs 2. If it is equal, weigh the other 2 as 1vs 1 and find the heaviest. If the 2 v 2 is uneven, take the uneven marbles and weigh them as 1 vs 1 and find the heaviest one.

### Design Verification Engineer at Apple was asked...

Aug 3, 2020
 Rewrite UVM phasing. 2 AnswersWhat exactly does this mean? Did they ask you to write all the phases along with their syntax or what exactly is the question here?Can you please give more details on the questions asked during your different rounds if you can recollect them?

### Design Verification Engineer at Qualcomm was asked...

Jun 26, 2017
 1)Should be ready to write some logics (C/Verilog/System Verilog) on the spot . 2)Blocking and Non-Blocking. 3)Fork/join types and applications. 4)Test bench architecture blocks.(asked to write a generalized code to implement gen and bfm).2 AnswersDid you get any reply from qualcomm?were you fresher or experienced?

### Design Verification Engineer at Apple was asked...

Mar 20, 2018
 1) Implement Linked list in hardware 2) LIFO using queues only2 Answers2. You can implement LIFO using a combination of queue.push_back +queue.pop_back OR queue.push_front+queue.pop_front2. You can implement LIFO using a combination of queue.push_back +queue.pop_back OR queue.push_front+queue.pop_front

### GPU Memory Hierarchy Design Verification Engineer at Apple was asked...

Dec 9, 2019
 How do you prevent the reordering of instructions, and how would you use this as a solution to the above issue?1 AnswerIn parallel computing, a barrier is a type of synchronization method. A barrier for a group of threads or processes in the source code means any thread/process must stop at this point and cannot proceed until all other threads/processes reach this barrier. Place a barrier between the instruction that works on them memory and the instruction that set the flag indicating that work is completed on that memory location.

### Senior Design Verification Engineer ( GPU ) at Apple was asked...

Mar 24, 2015
 Can you tell me how do you verify your block ?1 AnswerExactly this happned to me few months back. I was
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