The interview process was fairly straightforward but thorough. One phone interview and then on site interview. Phone interview consisted of 8 questions of moderate difficulty on basic single stage amplifiers and step responses. On site interview was pretty intense from 9am to 3:15pm with 6 people not including HR. Questions included current mirrors (matching and sizing), basic PLL (stability), switched capacitor circuits(noise), ADC basics (aliasing, transfer functions), feedback (output impedance), OTA structures (slew rate, bandwidth), supply independent biasing etc. A good preparation textbook is "Design of Analog CMOS Integrated Circuits by Behzad Razavi" and most of the questions had a form similar to end of chapter exercises and examples.