Liu Zhenming, Wen Haoran, Ayazi Farrokh
School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA 30308 USA.
StethX Microsystems Inc., Atlanta, GA 30308 USA.
Microsyst Nanoeng. 2023 Feb 21;9:18. doi: 10.1038/s41378-023-00486-3. eCollection 2023.
In this paper, a modification to the eigenmode operation of resonant gyroscopes is introduced. The multi-coefficient eigenmode operation can improve cross-mode isolation due to electrode misalignments and imperfections, which is one of the causes of residual quadrature errors in conventional eigenmode operations. A 1400 µm annulus aluminum nitride (AlN) on a silicon bulk acoustic wave (BAW) resonator with gyroscopic in-plane bending modes at 2.98 MHz achieves a nearly 60 dB cross-mode isolation when operated as a gyroscope using a multi-coefficient eigenmode architecture. The as-born frequency mismatches in multiple devices are compensated by physical laser trimming. The demonstrated AlN piezoelectric BAW gyroscope shows a large open-loop bandwidth of 150 Hz and a high scale factor of 9.5 nA/°/s on a test board with a vacuum chamber. The measured angle random walk is 0.145°/√h, and the bias instability is 8.6°/h, showing significant improvement compared to the previous eigenmode AlN BAW gyroscope. The results from this paper prove that with multi-coefficient eigenmode operations, piezoelectric AlN BAW gyroscopes can achieve a noise performance comparable to that of their capacitive counterpart while having the unique advantage of a large open-loop bandwidth and not requiring large DC polarization voltages.
本文介绍了一种对谐振陀螺仪本征模式操作的改进方法。多系数本征模式操作可以改善由于电极未对准和不完善导致的交叉模式隔离，这是传统本征模式操作中残余正交误差的原因之一。一个在2.98 MHz具有陀螺面内弯曲模式的硅体声波（BAW）谐振器上的1400 µm环形氮化铝（AlN），当使用多系数本征模式架构作为陀螺仪运行时，实现了近60 dB的交叉模式隔离。多个器件中与生俱来的频率失配通过物理激光微调得到补偿。所展示的AlN压电BAW陀螺仪在带有真空腔的测试板上显示出150 Hz的大闭环带宽和9.5 nA/°/s的高比例因子。测量得到的角度随机游走为0.145°/√h，偏置不稳定性为8.6°/h，与之前的本征模式AlN BAW陀螺仪相比有显著改善。本文的结果证明，通过多系数本征模式操作，压电AlN BAW陀螺仪可以实现与电容式对应物相当的噪声性能，同时具有大闭环带宽的独特优势，并且不需要大的直流极化电压。
