There were 2 parts : 1. brain teasers 2. Simple tech questions. First , the interviewer asked me the lightbulbs room question. (There are 3 light bulbs , you are in another room with the switches for each of them .. look at any brain teaser site ). Then he asked me how to get a constant voltage from a source voltage . I suggested voltage divider . We did a few equations and numbers there . Then used a BJT to achieve similar DC - DC conversion. It was a simple interview . However , I did not make it to their onsite interview. Their analog position is more of a power electronics position.