title: Optimization of single-phase, unidirectional transducers using three fingers per period.
abstract: Electrode width controlled (EWC) single-phase, unidirectional transducers (SPUDT) is widely used for low loss surface acoustic wave (SAW) filters. The insertion loss and fractional bandwidth of the filters are strongly related to the reflectivity of EWC cells. In order to achieve wide band and low loss simultaneously, it is necessary to obtain higher reflectivity. The relationship between geometrical configuration of EWC cells and reflection coefficient, (and transduction coefficient as well) is studied. Simulation results indicate that the reflectivity of the EWC SPUDT cell could exceed 5% on a 128 degrees Y-X lithium niobate (LiNbO3) substrate. Using such structure, low loss SPUDT test filters without weighting are fabricated. The measured 3 dB bandwidth is 3.9% and the insertion loss is 2.9 dB. The theoretical calculation is verified by the experiment.
authors.forename: Yongan
authors.initials: Y
authors.lastname: Shui
authors.forename: Jimin M
authors.initials: JM
authors.lastname: Lin
authors.forename: Haodong
authors.initials: H
authors.lastname: Wu
authors.forename: Ning
authors.initials: N
authors.lastname: Wang
authors.forename: Hui
authors.initials: H
authors.lastname: Chen
mesh_terms: D000162:Acoustics / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D009556:Niobium; D010087:Oxides; D011786:Quality Control; D012680:Sensitivity and Specificity; D013685:Telecommunications / Q000295:instrumentation*; D014159:Transducers
chemical_list: D010087:Oxides; D009556:Niobium; C091692:lithium niobate