A simple method for measuring the IM3 components of multi-stage cascaded power amplifiers considering the phase characteristics

A simple method has been proposed for the measurement of the output power and phase characteristics of the IM3 components appearing in multi-stage power amplifiers. By adopting a unique definition of the phase for the IM3 components that is independent of the delay time caused by transmission line and other instrument devices, it is possible to measure the phase, merely by using a vector signal analyzer. It is demonstrated that an accurate estimation of the IM3 characteristics of a two-stage cascaded power amplifier for cellular radio handheld terminals can be made by using the IM3 characteristics of the 1st and 2nd-stage amplifiers measured by the proposed method.