Internship questions:
1. Smith chart fundamentals - location of OC, SC etc
2. Impedance path of an RLC circuit from low frequency to high frequency on Smith chart.
3. MOS fundamentals - square law, current mirror mismatch, impedances looking into source and drain of MOSFET.
4. LNA design and tradeoffs, feedback paths, why do we use decoupling capacitors
5. Passive Circuits - even and odd mode of coupler, divider.
Fulltime Questions:
1. What is the difference between process and mismatch in Montecarlo? What is being varied in a Montecarlo simulation? What does FF, sf, FS pmos or nmos imply?
2. What are the capacitances involved in an RF switch that may cause signal leakage?
3. Passive inductor design - how can you increase the magnitude or Q of an inductor?
4. Noise Figure - Friis equation problems
5. Receiver sensitivity/defense
6. Linearity - P1dB and IP3 and how to calculate graphically and in the lab
5. Passive filter design
6. What does a QAM constellation look like?
7. Impedance matching on Smith chart
8. Transmission line matching on Smith chart
9. RC circuit responses - With diode included
10. Cascode amplifier benefits and how it helps in LNA design, how it helps reduce miller effect
11. Impedance looking into a node in a given mos circuit (basic but was not something I had seen before)
12. Mismatch in current mirror
13. For switch design, how to improve insertion loss, linearity. Methods to improve voltage division. Why do we stack FETs in switches? Switch configurations and topology. Power handling of a switch.
14. Layout questions related to a switch and how you can improve routing to reduce coupling.
I have usually had a good time being interviewed here. The senior engineers are usually quite pleasant and friendly. However, on my last interview I did notice that some of the early career interviewers weren't particularly professional; they tend to be rude during the presentation, and cut you off repeatedly, and not politely either. They come off as a little confrontational and literally guffaw if you are unable to quickly answer their question (I am an early career engineer, and found this particular interview unrealistically difficult for someone with 1 year of experience). Not everyone is like this of course, but I saw it in 2 people on the same team and could see that the senior members were a little uncomfortable as well. Not sure if they were treated the same way when they first interviewed and are emulating that.
They also take you for lunch during the full day onsite interview - do not let your guard down here, and think it's just a friendly chat. They are still interviewing you while you have your lunch. I sometimes got the feeling they interview employees from a competitor without really intending to hire them. I was afraid to present something from my past work due to intellectual property limitations but they insisted that that would be the best presentation topic for them. Be very careful and do not share any IP. It is quite difficult to prepare a presentation without giving away too much information - I was actually told by some of the members that they were unsure how I would be able to prepare such a presentation but they said I did a good job. For me personally, it involved a lot of reading papers and using those references since I worked on an obscure block. The funny part is there is a good chance they are likely to reject you if you accidentally reveal a vague detail or so.
These were great practice for me. Initially the full day interviews used to exhaust me - it was 4-5 back to back interviews and I could progressively feel myself making more mistakes towards the end of the day due to a lack of interviewing stamina. Your brain will tend to burn out and stall as you move forward, so practise with a friend as much as possible for a few hours before your interview. It requires a lot of mental stamina especially if you are not used to these long 6 hour interviews.
