There was 45 min technical phone interview scheduled after I received invitation email from Nvidia. The interview starts with the interviewer talking about his group's responsibilities and general information about how different groups inside Nvidia interact with each other.
The questions remembered so far are:
Setup time and hold time analysis: specify which part of a circuit contribute to the setup time or hold time violation?
super buffer: given a load capacitance, how to size inverters so that the overall delay would be smallest?
simple logic design: how to convert a two input nand gate into an inverter?
...
can only remember these questions so far... good luck!