I got an on-campus interview first via the campus job expo. In about two weeks I got a chance to have a phone interview with senior digital design engineers in multiple locations in the US.
The on-campus interview was more about behavioral questions. It was easier since we were talking face-to-face. Whenever I felt struggling I could use my body language to say I was thinking and went through how I developed the answers step-by-step. Some of the questions were about life experience, which I've never thought of.
The more important part is that I had to give a brief introduction to my current and previous projects. List the detail in the resume so the interviewer has something to read. They also asked me what was the greatest challenge in my project.
The phone interview is more energy-consuming. I had to prepare slides to introduce myself, mostly about all the projects I've done. Spend time on this part and practice. I talked for about 25 minutes. (which is a little bit weird since I was talking to the air with no response, but I guess that's how a phone interview works) They then asked me several decision-making related questions, also lots of questions about the projects. I would suggest interviewees make the slides as clear as possible. Explain the why, how and what thoroughly.
For the technical part, it was not too hard. I was told to draw some basic logic cells with transistors/logic gates.