This book treats the analysis and design of linear circuits. A circuit is said to be linear if it can be adequately modeled using only linear elements and independent sources. The hallmark feature of a linear circuit is that out- linear functions of the inputs. Circuit in are the signals produced by external s and outputs are any other designated signals. Mathematically, a function is said to be linear if it possesses two proper ties homogeneity and additivity. In linear circuits, homogeneity means that the output is proportional to the input. Additivity means that the out- put due to two or more inputs can be found by adding the outputs obtained when each input is applied separately. Mathematically, these properties are written as follows: