This book will help students and professionals understand the principle of Noise Figure (NF) and an efficient method to perform its measurement. While the primary emphasis of the book is for on-wafer measurement, it also addresses the effect of NF measurement under certain conditions. In this book, the NF measurement system is integrated with S-parameter measurement in order to give more accurate results, by including the reflection coefficient of input and output path into the consideration. The book begins with an introduction to the sources, definition and concept of NF. It goes on to provide an overview of NF measurement principle, which discussing the concept of NF measuring instrument, method to perform NF measurement, and also elements involved in the on- wafer measurement setup. Next, the book continues to discuss all the derivation of NF equation that integrates S-parameter formulation. A method of connecting the Device under Test (DUT) to the instrument is also shown graphically. As to ensure the method is correct, DUT used in the experiment is commercially available, where its specification has been published. Hence, results obtained are reliable.