# Interview Questions

interview questions shared by candidates

## Interview Questions

### DeltaV Development at Emerson was asked...

Describe some programs that you have written. 3 AnswersSo when you said generic programming, do you mean questions regarding the generic programming paradigm? Or just general programming questions? It was generic programming paradigms like oop, etc. They did not ask questions like list the output or anything like that. So, there's a possibility they may ask questions about Generic Programming (i.e. the STL class that Downing (If you went to UT) teaches during the summer). |

### Program Manager at Broadcom was asked...

3 boxes, 2 w/ 1 type item each & 1 mixed, labels are wrong, you get 1 pick from 1 box - can you correctly determine the right labels with 1 pick? 3 Answerslogic test by S/W Engineering director, test of logical thinking - he couldn't answer my physics based bar trick question in reply The answer is yes. The labels are all wrong, you pick one and you know it is correct. The other two are stil wrong. Switch the labels and they will be correct. Done. Let’s call the boxes A, B & Mix. Take item from the box marked Mix (must be single type since all labels are wrong), if the item found is B, it follows that: Box A (Mix), Box B (A) and of course Mix (B). If the item found is A, it follows that: Box A (B), Box B (Mix) and of course Mix (A). |

### Design Verication Engineer at Zoran was asked...

Given 3 consective numbers, the biggest and smallest are primes. Prove the number in the middle is divisible by 6. 3 AnswersSince The Number is divisible by 6 so it must be divisible by both 2 & 3.But below 6 no number is available which is divisible by 6.Hence each number must be greater than 6. Now the the three numbers which come after 6 are 11,12,13,in which 11 and 13 are prime numbers and the middle number is 12 which is divisible by 6. Similiarly we can she all the three numbers in which 1st and 3rd numbers are prime whereas the middle number is diviisble by 6 Hence proved! 5 - 6 - 7. YES. 3 - 4 - 5 NOT TRUE. One false example shows inability for proof. 3 consecutive integers: one must be divisible by 2; three integer; there is at least one which can be divided by 3; since the two-side integers are prime, then the middle one must can be divided by3 and 2; it means the middle can be divided by 2*3=6. Easy |

### Process Development Engineer at Cree was asked...

Can Si be used to make LEDs ? 3 AnswersSi can be used as a substrate in LEDs, but it cannot be used in the p-n junction because the bandgap energy is too small to produce visible light. Technically: Yes. But it has an indirect bandgap, so you really wouldn't want to. The energy bandgap of Si at room temperature is 1.12eV. Since the relationship between photon energy and wavelength is E(eV)=1.24/wavelength(micrometers), one can calculate that Si could emit a ligth in infrared optical spectrum: wavelength=1.24/1.12eV=1.11 micrometers. BUT, Si is indirect semiconductor! And therefore does not emit significant amounts of light due to the requirement of momentum conservation in optical transitions. |

### Engineering at Intersil was asked...

List all the possible uses for a diode 3 Answersrectifier, TVS, varicap don't forget Gunn Diodes can be used for an RF Relaxation Oscillator. III-V diodes are also good for light emission Diodes are also great temperature sensors And/OR gates Ionizing Radiation Detectors (Generate EHPs and inject carriers to create current) Almost all devices contain PN junctions (MOSFETs, MESFETs, DIACs TRIACs, BJTs, LEDs, Zeners, Tunnel Diodes, Vericaps) A better question would have been, "What diode is not made of a PN junction" Answer Metal-Semiconductor Junctions (aka Schottky Diode) Don't forget the classic diode detector. |

You are in a boat and you threw the anchor into the river. The anchor settled on the lake floor. What happens to the level of water before and after the anchor is dropped ? 5 AnswersDrops. Nothing happened to the water level because its a flowing river, not a standing body of water. Well which is it a river or a lake? Depends on the mass of and volume of the anchor. Is the mass enough to use the boat to displace more water than the volume of water displaced by the anchor being moved into the water? Show More Responses In general the level of the water drop because the density of the steel (for example) or other material of the anchor is bigger than the density of the water. I'm not in a lake I am on a river. |

What are some of your weaknesses? 3 AnswersThat sometimes I am too attentive to detail. I know this may be said alot, but it is true, I tend to pour over details to make sure there aren't any errors, which could sometimes consume too much time. was there a drug test? urine or hair? Employment offer is made pending urine drug test. |

how do you build a mux out of xor gates? 3 AnswersThe answer is you can NOT derive the equation of XOR and MUX by yourself, you will see Oh that is so not true.......! http://digitalelectronics.blogspot.co.il/2005/11/mux-out-of-xor.html |

which is hard to fix -- setup violation or hold violation? And why? 3 AnswersI answered setup, then they asked again how to fix the setup violation. Should be the hold time violation. Setup time violation can be solved by increasing the time period; however, hold time violation should be solved by inserting delay into the timing path carefully I think it depends on which stage the problem is detected. If after tape out, it's absolutely hold time because you cannot easily change the logic of chip. But if it is still in RTL coding stage, hold time may be easily fixed by adding some buffers. |

### ASIC Design Engineer at Broadcom was asked...

how to generate a clock divide by 3 4 AnswersAssuming that input clock is square wave and 50% duty cycle, Method 1: Clk / 3 is equal to Clk / (6/2). this means fist divide by 6 and multiply by 2. dividing by 6( use two DFF(D is tied to Q_b and it is connected to clock of 2nd DFF). multiplying by 2( create some delay and XOR the two signals(the signal after dividing by 6 and its delayed signal), But it's hard to make the output clock have 50% duty cycle due to precise delay control. so alternative method 1 is first multiply by 2 and divide by 6. Method 2. Use 2 edge counters(one for rising edge and the other for falling edge) draw the state machine that goes (back) to toggle state when both counters become 2. Sorry, Method 1 is incorrect. the possible method 1 is to delay the input clock and XOR the input clock and its delayed one(delay doesn't need to be precisely half period of input clock, which is good) then use a single rising edge counter to toggle when it counts 3 rising edges. this is glitch-free Please refer to: http://www.eetimes.com/document.asp?doc_id=1202359 Show More Responses Sorry above is wrong link. correct link: http://vlsiwizard.blogspot.com/2008/01/design-clock-divide-by-3-circuit-with.html |