Apple Hardware Engineer interview questions

I've interviewed on two separate occasions for hardware positions with Apple. Most (but not all) of the interviewers are nice enough. First interview had circuit design questions, the second did not. Both interviews were divided into several 1 on 1 interviews, 30 minutes each. If you're not selected (which I wasn't) they just leave you hanging. At first I thought it was just an lazy recruiter, but the second time it happened I realized that it must be a policy to not contact you or respond in any way if you are not chosen. Not a way to leave a good impression; after wasting time with them on the phone multiple times and taking time off to interview in person with them I don't think it is too much to ask for a form email letter to let you know you weren't selected (if their competitors can do it, I think Apple can as well). I doubt I will bother to interview with them again.

Difficult interview process. Must know mid to advanced analog hardware. Fundamentals are key. Will be asked to draw circuits, explain operation, and solve simple analog hardware questions. Expect multiple people on interview panel.