Understanding the Relevance of Harmonic Impedance Matching in Amplifi er Design

Today’s modern commercial and military communication systems are demanding better performance with regards to power, effi ciency, linearity and operating bandwidth. As such, extra considerations must be placed on designing the internal components of the systems, including the low-noise and power amplifi ers, to maximize performance. In order to reach higher effi ciencies, signifi cant research has been performed on designing high effi ciency amplifi ers by matching one or more harmonic impedances. An equally large effort has gone into designing commercial test systems which aid in the systematic identifi cation of ideal matching impedances at the fundamental and harmonic frequencies, referred to as harmonic load-pull, in order to maximize performance. Before venturing into a design project, it is important to ask several questions: Does the application require an amplifi er with harmonic matching? If so, which test system is best suited to reach the design goals? This paper explores various types of amplifi ers in order to identify which can or cannot take advantage of harmonic matching, and to compare and contrast various harmonic load-pull methodologies as they relate to amplifi er design.