”The Designer’s Guide to SPICE and Spectre” is not an introduction to circuit simulators. Rather, it assumes that you are already adept at the mechanics of operating a simulator and are interested in understanding how it works and increasing the skill and sophistication with which you use it. This book is intended to be a practical guide for circuit designers that routinely use circuit simulators. Problems that commonly occur are described with enough depth for you to understand why they occur, and then suggestions are given on how to avoid these problems. These issues are examined in the context of the circuit simulators Spice2 and Spice3, because the majority of commercial simulators are derivatives of these two programs, and Spectre, currently the most popular circuit simulator for integrated circuit design. Even though these three simulators are the focus of this book, it should be useful to the user of any circuit simulator.