Questions d'entretiens - Hardware engineer intern

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Questions d'entretien pour Hardware Engineer Intern partagées par les candidats

Principales questions d'entretien

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Microsoft
On a demandé à un Hardware Engineer Intern...21 décembre 2011

If you increase the width of a PCB trace, does it decrease or increase the trace impedance?

3 réponses

As 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. Moins

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. Moins

Microsoft

What happens to a signal integrity as you increase length and when there is return current?

2 réponses

It is better to keep the return path as short as possible, since it will form a loop antenna and will give EMI/EMC problems based on the loop length matching with operating frequency. Moins

Stairways in signals.

National Instruments

A time you had a bug and how you fixed it.

2 réponses

I talked about a program I wrote and how the recursion wasn't correctly operating and how I de bugged it. Moins

It's essential to demonstrate that you can really go deep... there are plenty of followup questions and (sometimes tangential) angles to explore. There's a lot of Hardware Engineer I Intern experts who've worked at National Instruments, who provide this sort of practice through mock interviews. There's a whole list of them curated on Prepfully. prepfully.com/practice-interviews Moins

Microsoft

What factors control the impedance of a trace?

2 réponses

width and thickness of the copper signal trace, thickness of the core or prepreg material on either side of the copper trace and dielectric constant of the core and prepreg material Moins

Trace width, copper thickness, and dielectric width

National Instruments

There was nothing unexpected. Although manager really wants to see your thinking process. He was very good at explaining the questions

1 réponses

Very nice company to work for

National Instruments

Questions are not difficult. The interviewer asked me to talk about the experience that what is the most difficult problem I have met and how I solve it

1 réponses

Through questions like this, interviewers are mostly trying to test your skillset (and its relevance to the role) as robustly as possible, so be prepared for multiple offshoots and followups. It could be a useful exercise to do mocks with friends or colleagues in National Instruments to get a real sense of what the interview is actually like. Alternatively Prepfully has a ton of National Instruments Hardware Engineer I Intern experts who provide mock interviews for a pretty reasonable amount. prepfully.com/practice-interviews Moins

Northrop Grumman

What is a time you did the right thing?

1 réponses

Used example from an old job.

Microsoft

Write program to check winner in a 2D 3x3 tic tac toe.

1 réponses

Check adjacent blocks in matrix.

Intel Corporation

What do you expect to see at the output when you connect 8 more inverters to an inverter?

1 réponses

not + (8* gate delay)+(8*track propogation delays)

Intel Corporation

Why do you need to calculate gain and phase?

1 réponses

Gain is a ratio of output voltage/input voltage, Phase is a frequency term. Both need to looked to verify the component/system behavior. Moins

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