Zolfagharloo Koohi Milad, Lee Seungku, Mortazawi Amir
IEEE Trans Ultrason Ferroelectr Freq Control. 2018 Aug;65(8):1468-1474. doi: 10.1109/TUFFC.2018.2839756. Epub 2018 May 23.
Intrinsically switchable thin film bulk acoustic resonator (FBAR) filters based on ferroelectric barium strontium titanate (BST) are presented. A 1.5-stage -network intrinsically switchable FBAR filter unit cell with a 3-dB fractional bandwidth of 3% at 2 GHz is systematically designed, simulated, and fabricated. The minimum insertion loss (IL) for the filter unit cell is 2.25 dB, representing the lowest IL reported for BST bulk acoustic wave filters to date, which is mainly due to its high BST resonators. Two 1.5-stage filter unit cells are connected in series to form a 2.5-stage filter, providing more than 25 dB of out-of-band rejection and OFF-state isolation between the input and the output ports. The measured input third-order intercept point (IIP) of the 2.5-stage filter is 47 dBm. Furthermore, the footprint of the fabricated filters is notably small, due to the high permittivity of BST.
本文介绍了基于铁电钛酸锶钡（BST）的本征可切换薄膜体声波谐振器（FBAR）滤波器。系统地设计、模拟并制作了一个1.5级网络本征可切换FBAR滤波器单元，其在2 GHz时的3 dB分数带宽为3%。该滤波器单元的最小插入损耗（IL）为2.25 dB，这是迄今为止BST体声波滤波器所报道的最低IL，这主要归功于其高Q值的BST谐振器。两个1.5级滤波器单元串联连接形成一个2.5级滤波器，在输入和输出端口之间提供超过25 dB的带外抑制和关断状态隔离。所制作的2.5级滤波器的测量输入三阶截点（IIP）为47 dBm。此外，由于BST的高介电常数，所制作滤波器的占地面积显著减小。
