Picosecond Imaging Circuit Analysis (PICA) is a new technique shown here to be applicable to the analysis of complex VLSI circuits. PICA was used to diagnose a timing failure in the early design of the G6 microprocessor chip. The fault occurred at high frequencies upon consecutive writes. Using PICA, combined with programmable array built-in self test (RAMBIST) techniques, the problem was traced to a race condition in the write control circuits. This allowed timely correction of the design for product implementation.