Simulating FBAR models in 3D allows designers to capture the filter's full performance. In this example, you will simulate a full 3D FBAR created using the symbol language and extract the impedance.

What is symbol?: Check out these articles to get more familiar with OnScale's scripting language symbol.

Model Description

Film bulk acoustic resonators (FBARs) can often exhibit spurious modes across the pass band which is one of design challenges an RF engineer faces. OnScale gives engineers the ability to quickly prototype a design to understand how effective it is removing these modes. This structure consists of a piezoelectric active layer (Aluminum Nitride) with Molybdenum electrodes on a silicon substrate at the sides of the air cavity. 


Download and Open the Model

Download: FBAR 3D 

OnScale Input Files have the file extension *.flxinp. To open the downloaded file:

  1. Open OnScale 
  2. Select Analyst Mode
  3. Select the Menu button in the top left of the application
  4. Select Open

Preview Model


Preview model is used to view the geometry dimensions and material assignment of a model to ensure the script is correct. To preview a model, select the Preview Model icon in the Home tab of the application ribbon.


Note: Preview model will display data from any grph commands that come before the prcs command. If you have more than one grph command, you can cycle through the graphics by continuously selecting Preview Model. To close the preview, select Stop Preview.

Run Model on Cloud 

To run the model on the cloud, select the Run on Cloud button in the Home tab of the application and follow these steps:

  1. Click Select and open the file you wish to run (fbar_3D.flxinp)
  2. Select Estimate
  3. Set CPUs to 8
  4. Select Run

Download Results

  1. From the Home tab, select the Storage icon
  2. Select the Refresh icon to refresh storage
  3. Select the Job Name from the dropdown menu
  4. Select the Download button
  5. Select Download All

Choose a directory to download the results to. These results will be stored in the folder: fbar_3D-YYYYMMDD-HHMMSS\1where YYYYMMDD-HHMMSS is the current date and time.

Switch to Post Processor

Post Processor is a suite of tools used to visualise and analyse output data generated from OnScale simulations. Switch to Post Post Processor.


What kind of analysis can I do in Post Processor? Find out here.

Analyse Results

To plot the impedance of the FBAR device, follow these steps:

  1. In File Explorer, navigate to the download directory and double click the file 'fbar_3D.flxhst' to open it
  2. In Results Manager, select the voltage time history 'pize top:Voltage' by left clicking it
  3. From the Home tab of the ribbon, select the Impedance icon to calculate impedance
  4. In the Frequency History section of the Results Manager, double click 'Impd:top.amp' to plot impedance amplitude
  5. In Plot Controls, tick Log yAxis
  6. In Plot Controls, set Minimum xAxis to 1.4e9
  7. In Plot Controls, set Maximum xAxis to 2.65e9
  8. In Plot Controls, set Minimum yAxis to 0.8
  9. In Plot Controls, set Maximum yAxis to 1e3