Verification of analog and mixed signal systems have been a very elusive technical milestone. Analog design is an art by itself. However, reality has brought us new requirements for complex analog/digital systems that require not only the original designer's insights for a complete verification but the implementation of adequate techniques for a more conductive verification approach.
Some of the latest approaches combine different techniques to attain a verification setup capable of checking complex systems.
At the U. of Texas, there are few groups/researchers working on IC verification. To name few