功放管匹配Freescale Semiconductor Application Note NOTE: The theory in this application note is still applicable, but some of the products referenced may be discontinued. AN721 Rev. 1, 10/2005 Impedance Matching Networks Applied to RF Power Transistors By: B. Becciolini 1. INTRODUCTION Some graphic and numerical methods of impedance matching will be reviewed here. The examples given will refer to high frequency power amplifiers. Although matching networks normally take the form of filters and therefore are also useful to provide frequency discrimination, this aspect will only be considered as a corollary of the matching circuit. Matching is necessary for the best possible energy transfer from stage to stage. In RF-power transistors the input impedance is of low value, decreasing as the power incr……