SAW metallization presents the designer with a great deal of variables. OnScale can be used to clearly present the design trade offs which exist, allowing the optimum design to be reached quickly.
In this example we vary both the aspect ratio of the SAW electrode fingers and the thickness of the electrode layer itself.
A schematic of the model and the two input variables can be seen below:
The key model parameters were as follows. Electrode thickness and electrode aspect ratio are set as design variables to be swept (indicated by *)
|Design Variable||Description||Default Value|
|elec_thk *||Thickness of electrode||200 nm|
|subs_thk||Thickness of substrate||7.5 µm|
|fin_pitch||Finger pitch||1.3 µm|
|aratio *||Metalization aspect ratio||0.5|
|nfing||Number of pairs of fingers in full device||100|
|fin_len||Length of fingers||50 µm|
|piezo_mat||Piezoelectric material||lt (LiTaO3)|
|cut_ang||Rotated y-cut angle||0.5|
Input variables were swept as follows:
- Aspect ratio: 0.4 – 0.6 (10 steps)
- Electrode thk: 180 – 220 nm (10 steps)
Simulation Sweep Results
The full simulation sweep was completed in 3 minutes when using 8 cores per simulation and had a total cost of 40 core hours.
Using the outputs from the simulations, it is possible to calculate the device impedance, Q factor and resonant frequencies. These outputs can all be plotted against the input variables to provide an insight into the device performance. Results are plotted below.