EE Interview Questions 2

Posted by bob on November 13, 2013

Let's try some more interview questions. The numbering for the questions continues from the previous post.

Remember that there is not one "right" answer.  There might be several good answers and there might be several poor answers that make me aware that you have not had much experience.  It is unlikely that any single answer would ever make me judge you harshly.  Indeed, I have been known to hire people who got several answers very wrong.  But it was the way they discussed their answers, especially after some mid-course correction that made the difference in my opinion.

4)      If you connected an oscilloscope to a signal on a circuit board and saw a waveform that looked roughly like the one below.

  1. What kind of signal are you probably observing? 
  2. Can you explain some of the parts of this signal?
  3. What problems might affect a signal like this?



5)      Now let’s assume that we have a relatively low frequency signal like audio going through an amplifier (perhaps an operational amplifier) stage.  Assume that the input and output waveforms shown are what you see with your oscilloscope.

  1. What kinds of problems in the circuit could cause the output to look like this?
  2. What would you check first in the circuit?  (Describe your debug process.)
  3. What effect would you expect to see in a frequency-domain plot of the output signal?
  4. Do you know what this effect might be called?




6)      Let’s look at a printed circuit board layout.  Assume that this is a two-sided PCB, with red as the top layer and blue as the bottom layer. 

  1. If we have a high speed digital driver at point A and the receiver at point B, how would you route the signal from point A to point B on the top (red) layer? 
  2. What problems might still happen and what tradeoffs are you making here?


Okay, this ends the second three questions.  The next posting will have 4 questions, giving us a nice total of 10 questions.  If you are feeling less than 100% confident in your answers, that is okay.  Time to do some research.