This is testament to the falling ethics of interviewers or of companies these days. There were two rounds of phone interviews. Sparing the details, the first was with a Director/Hiring Manager who insisted that I not leave the company if I was offered a position as he would have spent time and money into hiring and training me. (The interview took place on a Sunday evening at 10:00 pm). Questions asked included TIA, op-amp compensation, noise-figure calculation, feedback etc.
The second phone interview was setup as a precursor to an on-site interview. The impression the interviewer(s) left me with was one of being relatively competent, but having bookish knowledge and unsure of the answers to questions that they posed themselves. Questions asked included noise figure calculations, RF LNA, Mixer fundamentals etc.
They later withdrew the invite to an on-site interview stating the project could not wait long periods for my (out-of-country) visa to be processed despite knowing this at the start of discussions.
All in all, it seemed the company culture was one of good learning opportunities but where one is worked to the limits.