The cell to be characterized is embedded into a test structure where it is driven by the real live drivers. This helps to capture the coupling between a cell and its drivers on silicon properly, and also eliminates any unrealistic assumptions about the shape of the input waveforms. The inputs buffers are loaded with fixed capacitors to generate different input slope conditions. Outputs of the cell are loaded with different capacitive loads while measuring input to output delays. For a discussion of the limitations of static delay calculation, please refer to delay accuracy section of Frequently Asked Questions.
Same setup is used for measuring power, supply currents and input loads.
This is two parameter model with intrinsic delay and load factor. It has no parameter to account for input slope. However, LibChar will still calculate the best fitting parameters measuring delays at different input slopes. This is a three parameter model which takes into account input slew rates as well. It is the same as Synopsys generic cmos model.