This book describes a measurement system that was set to perform comprehensive measurements on RF power amplifiers. Data obtained from the measurements is then processed mathematically to plot 3-D graphs of the basic parameters affected or generated by nonlinearities of the amplifier i.e. gain, efficiency and distortion .Using a class AB amplifier as the DUT, two sets of signals – both swept in power level and frequency - were generated to validate the method; a two-tone signal and a WCDMA signal. The measurement setup yields 3-D plots of variations of gain, efficiency or distortion versus any arbitrary range of frequencies and input levels. Moreover, the measurement tool can be used to plot traditional 2-D plots. The test signals were generated by computer then sent to a vector signal generator that generates the actual signals fed to the amplifier. The output of the amplifier is fed to a vector signal analyzer then collected by computer to be handled. MATLAB® was used throughout the entire process. The system can be a very useful tool for RF amplifier users and designers. It is also useful for students who are working to understand RF amplifiers and their common trade-offs.