Surface acoustic wave impedance element ISM duplexer: modeling and optical analysis

• Published in: IEEE transactions on ultrasonics, ferroelectrics, and frequency control ferroelectrics, and frequency control, 2001-05, Vol.48 (3), p.652-665
• Main Authors: Makkonen, T., Kondratiev, S., Plessky, V.P., Thorvaldsson, T., Koskela, J., Knuuttila, J.V., Salomaa, M.M.
• Format: Article
• Language: English
• Subjects: Acoustic measurements; Acoustic waves; Acoustical measurements and instrumentation; Acoustics; Antenna accessories; Antennas; Circuit simulation; Computer simulation; Duplexers; Exact sciences and technology; Fabrication; Fundamental areas of phenomenology (including applications); Imaging; Impedance; Mathematical models; Optical surface waves; Physics; Predictive models; Reduction; Surface acoustic waves; Surface impedance; Textile industry; Ultrasonics, quantum acoustics, and physical effects of sound
• ISSN: 0885-3010; 1525-8955
• DOI: 10.1109/58.920688

Surface acoustic wave (SAW) impedance element antenna duplexers provide compact, high performance, front-end components apt for industrial fabrication. We describe investigations on the design and modeling of a compact ISM antenna duplexer fabricated on a 36/spl deg/ YX-cut LiTaO/sub 3/ substrate based on SAW impedance elements. In particular, we have performed 3-D modeling of the inductive and capacitive electromagnetic couplings caused by the package parasitics for the duplexer. The use of a 1:3 IDT structure for the reduction of the passband width is discussed. The frequency response of the duplexer is predicted with the help of circuit simulation; the modeling is refined by optimization of the model parameters to improve the fit between the measured and simulated responses. We also report scanning optical imaging of the acoustic field within the resonator structures with the help of laser interferometry; this provides insight into the loss mechanisms beyond that attainable in mere electric measurements.