A basic understanding of circuit design is useful for many engineers—even those who may never actually design a circuit—because it is likely that they will fabricate, test, or use these circuits in some way during their careers. This text provides a thorough and rigorous explanation of both analog and digital transistor-level circuit design with a focus on the underlying principles of how different circuits work—instead of relying completely on design procedures or “rules of thumb.” In this way, students develop the intuition that is essential to understanding and solving design problems.