Hardware engineer Interview Questions | Glassdoor

# Hardware engineer Interview Questions

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## Top Interview Questions

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### RF Hardware Engineer at Qualcomm was asked...

Dec 1, 2011
 What are the effects of a mismatched circuit?4 Answersunwanted heat and intermodulation productsIIP2 & DC OffsetsMismatched circuits can produce excess heat, DC offsets, intermodulation products, and other unwanted complications.Show More ResponsesIN the digital domain, zero crossings and ISI , as well as DC offset can be compromised.Loss of received signal strength with distortion, Overheating and damage to TX drivers

Apr 10, 2014

Aug 1, 2014

### Senior Hardware Verification Engineer at NVIDIA was asked...

Jan 29, 2010
 Describe a function to check if an integer is a power of 2.6 AnswersFor an integer n: If n is less than 1, return false. If the bitwise & of n and n-1 is 0, return true. Otherwise, return false.Write the number in binary and count the number of ones in that.If the number os ones is only 1 then it the number is indeed a power of 2first check if no is 1 then return false else write the number in binary and then check number of ones in that.if only one 1 is there then its a power of 2Show More ResponsesI think the main idea is to use recursion function, for the integer which is larger than 0, if it is 1 return true, else return function(n-1)See if the sum of all bits is 1. If that's the case then the number is a power of 2.function int power2(int i); if (i%2==1) return 0; else if (i/2==1) return 1; else return power2(i/2); endfunction

### Staff Hardware Engineer at Qualcomm was asked...

May 2, 2013
 If you have a 600 digit number with only 0's and 1's, and exactly 300 1's, can the number be a square?6 AnswersNoI am trying to undersatnd why you say the answer is No. for a 6 bit binary number, of which 3 bits are exactly 1s. 25 and 49 are possible such numbers that happens to be a square... Why can't this possibility extend to a 600 bit binary number?The answer should be YES: @gustion: your example with 49 (7 pwr2) is correct but with 25 (5 pwr2) is incorrect. 7 in binary is 111 (3 1-bits is half of 6 bits), but 5 in binary is 101 (2 1-bits does not equal half of 6 bits). In general, any binary number with n-bits, half of which are 0's and half are 1's is a square of a binary number with half the number of bits, all being 1-value bits. In addition, the number's magnitude will be n/2-1 1-bits followed by n/2 0-bits followed by the last 1-bit. For example, lets say we have a 16-bit number. The number which will have 8 1-bit and 8 0-bit binary digits and also be a square is: 1111 1110 0000 0001 (7 1-bits followed by 8 0-bits followed by 1-bit) and this number is a square of 1111 1111 Binary number with 600 bits and 300 1-bits will have a magnitude of 299 1-bits followed by 300 0-bits followed by 1-bit, and it will be a square of a 300-bit number with the magnitude of 300 1-bits.Show More ResponsesWell on a simple note, 9's binary is 1001, a 4 digit binary with two 1's and two 0's, and is a perfect square. The same analogy should also be true for any such number.can someone explain why this pattern works?Because (2^n - 1)^2 = 2^(2n) - 2 * (2^n) + 1 = 2^(2n) - 2^(n + 1) + 2^0. Such that bit n + 1 to 2n -1 will be 1, bit n to 1 will be 0, and bit 0 will be 1, which makes it n bits of 1 & n bits of 0. You can test 15^2 = 225 to understand it.

### Hardware Engineer at SandForce was asked...

Jun 25, 2009
 10 Gbytes of 32-bit numbers on a magnetic tape, all there from 0 to 10G in random order. You have 64 32 bit words of memory available: design an algorithm to check that each number from 0 to 10G occurs once and only once on the tape, with minimum passes of the tape by a read head connected to your algorithm.3 AnswersGood luck with that. You'd better come up with an answer in <10 minutes.a 32 bit number can have unique values from 0 to (2^32)-1. Meaning it can have max value of upto (4 Giga -1). If there are more than 4 Giga locations, then there is repetition which is obvious, even before one starts the question. Usually, questions of repetition can be solved by "XOR"ing all the values. If the value is not zero then some number is repeated. One should solve around that angle.I think the employer was asking about the binary search tree algorithm. This is how I would have answered it. 1. First create a binary tree for all the data(which can be 4 gb only) 2. Every time a new data is to be inserted into the memory, we should traverse the tree to search if the element is present: if present, return "element already stored and so we cannot insert it again" else, insert the element into its appropriate place. Since, its a binary tree we can search an element in (log n) time and with minimum number of passes.

### Electrical Hardware Design Engineer at HP Inc. was asked...

Feb 14, 2018
 Q: What does a capacitor look like at high frequency?4 AnswersA: A capacitor looks like a capacitor, inductor, and resistor in series at high frequency.An openA shortShow More ResponsesIts an short circuit at very high frequencies. Look at the impedance for a capacitor and you'll notice that the frequency is inversely related to it. (also note that capacitor impedance is purely reactive). Therefore, as frequency increases the impedance approaches 0, which acts like a short. (an inductor is the opposite)

### Senior Hardware Verification Engineer at NVIDIA was asked...

Jan 29, 2010
 Describe a circuit that implements the following truth table using only NAND gates. A B OUT 0 0 1 0 1 1 1 0 0 1 1 17 Answers((A NAND B) NAND C)out = (A NAND (B NAND B))out = ((A NAND A) NAND (A NAND A)) NAND (B NAND B)Show More ResponsesOUT = (A NAND (B NAND 1)) or out = (A NAND (B NAND B)) like what anonymous said. One or more comments have been removed. Please see our Community Guidelines or Terms of Service for more information.

### Hardware Engineer Intern at Microsoft was asked...

Dec 21, 2011
 If you increase the width of a PCB trace, does it decrease or increase the trace impedance?3 AnswersAs you increase trace width, impedance is lowered.The question is a little tricky (not really tho). The impedance of a straight line is described by Z=R+jX, where R is the resistance and X is the reactance. As the width of the trace is increased, R decreases. If we assume that there is no inductance, then the impedance will go down, as X=1/(jwC), and C=W*L*C0. However, in a very inductive space (like trace is curly and goes around itself a lot), then X = jwL, thus increasing the complex part of the impedance. I would go with the decreasing impedance, as on the PCBs resistance is the dominant term.If you increase the width of the pcb trace then it will help decreasing the resistance of the PCB trace. I give you a simple analogy if for example we consider the inductance as the negligible amount then, ( R=c (L/A)) where c is resistivity . And we are increasing the Area of cross section that is A. Then that is inversely proportional to the resistance and hence it decreases the impedance.

### Haptic Hardware Engineer at Apple was asked...

Jun 8, 2016
 List all the possible solutions to make a hole in any metal. 2 minutes are given.3 AnswersDrill Laser High pressure water jet Friction drill PunchDrill Punch Laser Water Jet Plasma Cut Gas Torch Grind Cut with Knife Cut with oscillating sawalso wire cut, using chemical like acid, arc welding
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