Abstract: A device characterization concept to test a semiconductor design by simulation includes storing a defined pattern and defined pattern analysis length, an analysis time and a defined number of characterization design parameters as a list in a memory simulating a device under test (DUT). The design parameters are a function of different customer-like pattern and test conditions according to the equation characterize design parameters (randomize/optimize (input pattern, test condition)) by using a pattern and condition variation and optimization technique (PCVOT), so that the design parameters are a function of different customer-like pattern and test conditions and that the range of design parameters variation with respect to the different input pattern or condition or combination of them is analyzed until the worst case is detected.