A Dynamic Measurement Method for Determining the Output Impedance of an RF Power Amplifier

Described herein is a novel approach for measuring the output impedance of a radio frequency (RF) power amplifier under actual operating (dynamic) conditions. The procedure involves loading the amplifier with three different values of resistance which are close to the intended load resistance value. Three separate experiments yield load excitation voltages (or powers) which permit direct calculation of the source complex impedance. The precision of determining the source impedance of the amplifier under test is only limited by the known tolerance of load resistance values used and the accuracy of measurements taken. The most important attribute of the technique described is that no requirement exists to alter the operating frequency. Also, the technique is applicable at microwave frequencies.