This book provides comprehensive knowledge, aimed at practicing integrated circuit design engineer or researcher, to learn and design a low noise amplifier (LNA) for single and multiband applications. The content is structured in a way so that even a beginner can follow the design method easily. This book features the following characteristics: different types of LNA designs (with key building blocks) are discussed, and detailed analysis is given for each LNA design, which covers from the fundamental and principal knowledge to the justification of the design approach. Detailed design approaches are using 180 nm and 130nm CMOS technologies, purposely presented in this manner to give exposure to the design of LNA under different technologies. The LNAs in this book are designed for GSM, WCDMA and WLAN standards, but the same method can be used for other frequencies of operation. Comprehensive analyses on the extreme or corner condition effects are highlighted. Besides, detailed derivation of equations relating to the parameters of the LNA’s performance metrics help LNA designers in understanding how the performance metrics of the LNA can be optimized to meet the desired specification. Electromagnetic analyses using Sonnet, an electromagnetic tool able to replace the conventional post-layout simulation with resistance and capacitance parasitic extraction for more accurate frequency performance prediction are presented. The electromagnetic method is proposed to be used in the LNA design as it can accurately predict the LNA’s performance before tape-out for first-pass fabrication. MATLAB codes are provided to generate important S-parameters and noise figure values.