Yang Qingrui, Pang Wei, Zhang Daihua, Zhang Hao
State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072, China.
Micromachines (Basel). 2016 Aug 5;7(8):133. doi: 10.3390/mi7080133.
High-performance bulk acoustic wave (BAW) filters have been widely applied in the advanced radio frequency (RF) wireless communication systems in the past decade. However, the demand for filters with large bandwidth, up to 10%, still puts a significant stress on the typical aluminum nitride (AlN)-based BAW filters. In this work, a modified lattice configuration is proposed to achieve a wideband filter response using AlN-based BAW resonators. The single stage of this novel topology comprises two auxiliary inductors paralleled in the balanced input and output of the conventional lattice topology. In multi-stage configuration, adjacent two auxiliary inductors can be combined into one; thus, the number of auxiliary inductors decreases exponentially, enabling the compact integration of filter chips. The circuit analysis is performed to reveal the working principle of this configuration. The systematic design methodology is developed ranging from the schematic design to the electromagnetic (EM) simulation. For proof-of-concept validation purposes, a prototype film bulk acoustic wave filter in this configuration is designed and fabricated. The measured 3-dB bandwidth is 400 MHz at the central frequency of 3.25 GHz (12.3% relative bandwidth), which demonstrates a huge superiority in contrast with the conventional ladder and lattice topologies.
在过去十年中，高性能体声波（BAW）滤波器已广泛应用于先进的射频（RF）无线通信系统。然而，对于带宽高达10%的滤波器的需求，仍然给典型的基于氮化铝（AlN）的BAW滤波器带来了巨大压力。在这项工作中，提出了一种改进的晶格配置，以使用基于AlN的BAW谐振器实现宽带滤波器响应。这种新型拓扑结构的单级包括两个辅助电感，它们并联在传统晶格拓扑结构的平衡输入和输出端。在多级配置中，相邻的两个辅助电感可以合并为一个；因此，辅助电感的数量呈指数级减少，从而实现滤波器芯片的紧凑集成。进行了电路分析以揭示这种配置的工作原理。开发了从原理图设计到电磁（EM）仿真的系统设计方法。为了进行概念验证，设计并制造了这种配置的薄膜体声波滤波器原型。在3.25 GHz的中心频率下，测得的3 dB带宽为400 MHz（相对带宽为12.3%），与传统的梯形和晶格拓扑结构相比，显示出巨大的优势。
