Y. Zhu, N. Wang, C. Sun, S. Merugu, N. Singh and Y. Gu, "A High Coupling Coefficient 2.3-GHz AlN Resonator for High Band LTE Filtering Application," in IEEE Electron Device Letters, vol. 37, no. 10, pp. 1344-1346, Oct. 2016. doi: 10.1109/LED.2016.2602852
This letter reports an aluminium nitride (AlN)-based micromechanical resonator with high-effective coupling
coefficient (k2eff) and low insertion loss (IL), which are comparable with those of Film Bulk Acoustic Resonators (FBARs). The in-house-fabricated resonator comprises of lithographically patterned top and bottom molybdenum interdigitated electrode fingers and a layer of 1-μm-thick AlN sandwiched in between. Synergetic inter-mode coupling between the constituent thickness mode and the lateral mode can be
realized within a wide frequency range, which can be treated as a subcategory of degenerated cross-sectional Lamé mode, enabling the capability of lithographic tuning of resonant frequency yet not compromising k2eff. Measurement results show that the designed 2.3-GHz resonator achieves a k2
eff of 6.34% and an IL of 0.26 dB upon direct connection to a network with 50-Ω termination, making it a promising candidate for Wireless Local Area Network (WLAN) and high band Long Term Evolution (LTE) band selection filtering applications.
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