Wafer Bonded TC-SAW - 3D Unit Cell

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 TC_WB_Mode_Shape.png 

Modal displacement of a wafer bonded TC SAW at series resonance

Model Description

This simple unit cell model of a single port Temperature Compensated (TC) Surface Acoustic Wave (SAW) filter allows rapid simulation of device performance. This allows a very wide range of designs to be explored before moving to more complex full 3D simulations. This particular device uses a wafer bonded layer of Lithium Tantalate (LiTaO3) on top of a silicon substrate.

The model comprises a pair aluminium electrodes on top of the LiTaO3 piezo layer. This structure sits on a silicon substrate. The model is set up to simulate a Y-cut, which can be rotated to the desired angle - set to 36 degrees by default. The base design generates a leaky mode at 1.5 GHz using a finger pitch of 1.3 µm.

TC_WB_Geometry.png

Model Geometry

 

Design Variables
The base model allows the following design variables to be adjusted. By default electrode thickness and LiTaO3 thickness are set as design variables to be swept (indicated by *).

Parametric Variable Description Default Value
 subs_thk Thickness of substrate  10 um
 elec_thk* Thickness of the electrodes  200 nm
 piezo_thk* Thickness of piezo layer  600 nm
 fin_pitch SAW finger pitch  1.3 um
 aratio Electrode aspect ratio  0.5
 nfing Number of finger pairs 100
 fin_len Finger length 50 um
piezo_mat Piezo material lt
cut_ang Y-cut angle 36

Outputs
A wide range of outputs can be generated, including:

  • Electrical Impedance / admittance
  • S parameters
  • Mode Shapes (Harmonic Analysis)
  • Energy flow analysis

 

TC_WB_Impedance.png

Typical Impedance output

Runtime Statistics

Degrees of Freedom  6800
Solve Time  63 secs (8 CPUS)
Core Hours  0.14
Memory Usage  72 MB

Files

The following input files are required to run this model:

Wafer Bonded TC-SAW

 

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