Thickness Shear Mode Quartz Oscillator
Application ID: 4707
AT cut quartz crystals are widely employed in a range of applications, from oscillators to microbalances. One of the important properties of the AT cut is that the resonant frequency of the crystal is temperature independent to first order. This is desirable in both mass sensing and timing applications. AT cut crystals vibrate in the thickness shear mode—an applied voltage across the faces of the cut produces shear stresses inside the crystal. This example considers the vibration of an AT cut thickness shear oscillator, focusing on the mechanical response of the system in the frequency domain. Setting up a COMSOL model using the various standards set up to define piezoelectric material orientation is covered in detail (note that the details of the standards are covered in a COMSOL blog post). The effect of a series capacitor on the mechanical resonance is also considered. Adding a series capacitance is a technique frequently employed to tune crystal oscillators.
This model example illustrates applications of this type that would nominally be built using the following products:
however, additional products may be required to completely define and model it. Furthermore, this example may also be defined and modeled using components from the following product combinations:
- COMSOL Multiphysics® and
- either the Acoustics Module, MEMS Module, or Structural Mechanics Module and
- either the MEMS Module, RF Module, or Wave Optics Module and
- either the AC/DC Module, MEMS Module, Plasma Module, or Semiconductor Module
The combination of COMSOL® products required to model your application depends on several factors and may include boundary conditions, material properties, physics interfaces, and part libraries. Particular functionality may be common to several products. To determine the right combination of products for your modeling needs, review the Specification Chart and make use of a free evaluation license. The COMSOL Sales and Support teams are available for answering any questions you may have regarding this.