This module we will finish with small dimension effects, and then talk about models for circuit simulation (the circuit designers among you are probably already using such models). We discuss what it takes to make a good model for circuit simulation (among other things: a lot of caution and care, and about 20,000 lines of code!), and how you can spot possible problems with such models. Although models for circuit simulation include capabilities we have not yet discussed, such as charge modeling, we think you know enough about models at this point to be able to follow this general discussion (which is out of sequence – it’s from Chap. 10 in the book, where you can find much more on the subject).