Home > Examples > Small and Large Signal Simulation of RF Power Amplifiers

Small and Large Signal Simulation of RF Power Amplifiers
  

§  To start designing this device, first click on Model   located in your Control Panel.

§  Go to the Options drop down menu, select Units, and set your length to mil.

§  Then, in the Options drop down menu, select Settings.

§  Make sure you have a metal at the bottom of your substrate by selecting Yes for Metal at Bottom, and set your Frequency Range from 1 to 10GHz, then press OK.

§  Turn off the radiation feature by selecting No for Radiation.

§  You can make all your necessary changes to Dx, Dy, and Dz in the Control Panel. Keep in mind, however, that these values need to be lower than the Max value posted above (with Max being a function of the dielectric constant, the frequency range, and the mesh density).  Set Dx=10, Dy=33.3, Dz=10. (Tip: for faster simulations, Dx, Dy and Dz may be ste as close as possible to MAX, which can be achieved by increasing/decreasing the maximum frequency range in the Options->Settings)  
o  You can also set proper bridge depth (if applicable), line width  and mesh density  in Settings, which will help the software generating a proper initial mesh.
o   mesh density is in cells/wavelength, the wavelength here is the minimum one associated with the upper limit of the simulation frequency range.
The Settings window would look like this for this design:

§  Go to Chip Designer by clicking on the icon. You can now start editing your metal in 2D.

§  Click on the Edit drop down menu and select Change Grid Dimensions. Set the dimensions to 40x95.

§  To start editing your metal design shape, first click on the Draw Rectangle icon, then click and drag to form your first rectangular shape. You can edit your metal shapes’ dimensions and location by Going to Edit Modeand:

o   Using your mouse to click, drag and resize your shapes, or just clicking on the metal shape and using your arrow keys to position it.

o   Or you can just click on the desired shape, and manually enter its exact dimensions and location in the Properties panel located on the right.

To get out of Edit Mode, simply click on the  icon again.                                   

§  Draw the first pair of rectangular using the following parameters:

and your design would look like:

§  Place the second pair of rectangular to complete your metal design:

and the 2-D views of the design should look like this:

§  Save and close window to get out of chip designer.

§  Click on , then set the From Metal and To Metal to be Square 5 and Square 6 in the component properties table, and place the FET circuit model at the central location between these two metals.

The parameter table for this specific FET circuit is displayed below:

§ Users are free to import any models working for them, such as TOM, Statz, Angelov, Verilog-A as well as any foundry-based model.  Furthermore, EM-supreme can aslo be customized to fit your specific project needs. 

§  To finalize your design, you will now need to add port. To do so, simply click on the port symbol, and then add the port to your metal. When you are done adding your port, press Esc on your keyboard.  (Tip: Remeber to use the View functions such as Pan and Rotate to have a better visual of the port area) 

The overall design would be like this:

§  Now that you ready to start running the simulation by clicking on the Simulation button.

§  When it is completed, you can view the Results by clicking on.

§  When you first open up your Results window, the two graphs should look blank.

§  To start viewing the graph results, click on the desired Port File located in the S-Parameter and Smith Chart Control Panels.

§  The curves of S11 and S21 are shown below:

We can see that the S21 drops from 17dB at 1GHz to -22dB at 10GHz, and S11 is close to 0dB at lower and higher frequency band due to the mismatch. 

§  You can set the exact specifications of your graph by changing the Range in your S-Parameter and Smith Chart Control Panels.

We can only see S11 and part of S21 in the chat, this is because the amplitude of the other part of S21 is much greater than 1, which is out of the range of the Smith chat can display.

§  By choosing Yes for the large-signal item in the settings window, we can check its large signal responses.

It shows that the fundamental component is keeping linear and drops about 1 dB around 31 dBm “i.e. output 1-dB compression point”. Also, the harmonics are 30 dBc below the compression point.

See also