Modeling a longitudinally coupled dual-mode leaky-SAW resonatorfilter with enhanced upper-sideband suppression

摘要

Recently, it has been experimentally reported that enhancednupper-sideband suppression of a longitudinally coupled (first/third)ndual-mode leaky SAW (LSAW) resonator filter may be obtained bynincorporation of a selectively valued capacitor between input and outputnterminals. In this paper, coupling-of-modes (COM) and bandstop-filternmodeling is applied to realize this enhanced suppression. Tradeoffs arenexamined between upper and lower sideband suppression levels caused bynthe ensuing capacitive coupling between input and output terminals. Goodnagreement is obtained between this theory and reported experimentalnresults for an 800-MHz band cellular filter