On-Wafer Intermodulation Distortion and Third Order Intercept Measurements Using Computer Controlled Microwave Tuners

Intermodulation distortion (IMD) and third order intercept (TOI) have been used for some time to determine the linearity of microwave amplifiers. By using a computer controlled microwave tuner system commonly used for load pull measurements, this measurement can be performed on discrete devices, and the effect of load or source impedance on the linearity characteristics evaluated. Combined with on-wafer measurement techniques, the resulting test system can quickly and non destructively characterize relatively large numbers of devices. This information adds to the tools available to the circuit designer for amplifier development. In this paper the development of such a measurement system is discussed, along with the sources of error discovered.