I had the first round interview on campus, after applying to the company through our college website. I was a bit surprised since I did not visit them during career fair (their line was too long).
The first round interview was with their college recruiting HR manager. Although it was STAR questions, the interview flows more likes a conversation than Q&A style.
I was invited to a second round interview at Houston and it was a 2 day event. The first day was not an interview, we just went there and got to know the hiring managers, got a tour of the site and had dinner with some engineers.
The second day we had the interviews. They were hiring 2 electrical engineers for the drilling department. I had 2 interviews with 2 different team. The interview really depends on the interviewer, the first guy I had was more technical orientated, so he asked how I would design a certain circuit, asked about systemverilog, simple DSP knowledge, and basic programming skill.
The second interviewer focused on my previous projects. He asked me to draw out the circuit of a previous design I made. He also asked about other technical aspects of old projects that I have done.
Side note: On the same day, there were also mechanical engineers interviewing for the company, they all had behavorial questions only.