Vandana Duff

Design a Low Pass Filter in 3 Steps

Blog Post created by Vandana Duff Employee on Apr 27, 2017

I was excited and intimidated when I took the opportunity to write this blog post for Keysight EEsof EDA.  I had some exposure to what Keysight ADS is and what you can use it for in college – but to write tutorial blogs to assist engineers who design the next satellite that will be launched into space?  That seemed like a daunting task. 


I participated in a training session that walked me through designing a Low Pass Filter and I wanted to share it with you. 

I was able to design this low pass filter in 3 easy steps.


Step 1:  Start up ADS and create your workspace. 

If you don’t have ADS get a free 30-day trial here.


Choose your directory and name your workspace. 


Select only the Analog/RF library, and uncheck all others if needed.  This means that the components from the RF/Analog library will be available for later. 



Name your library, and select the Standard ADS Layers .0001 mil layout resolution.  Make sure everything looks correct, and click “Finish”.


Your workspace is now created!  


Step 2:  Build your schematic.



By expanding to cell view, you can now see that your schematic pops up in your workspace. 




Select the components you need by clicking on the component and dropping it on the schematic page.  You can rotate parts by using the toolbar icon or cursor on or use the cursor to drag the handle on the component.  Connect up the components with the wire button, and don’t forget to ground your circuit! 




To change the values, units, or even the name of your component, double-click the component and make changes as needed.



Step 3:  Set up an S-Parameter Simulation.

Select the “Simulation-S_Param” on the palette and drop it on your schematic area.  Insert the port terminations, and make sure to ground them.



To set up the simulation, double-click the gear on the schematic. Change the step size and frequency range.  I used a step size of .5 going from 1 GHz to 10 GHz.  Click OK, and now you are ready to simulate!


Click the gear (alternatively, use F7), select simulate, and fix any errors that may have shown up.

ADS has a variety of different plots.  I’m going to create a rectangular plot. 



Select the rectangular plot and select which S-parameter measurement you want to use, select your units (S-parameters are usually measured in dB), and click ok. You can zoom in and out with your mouse, and view all with this icon:



Put a marker on the trace, and you can move them around with the red arrows. 




Now I’ve created a low pass filter and plotted an S-parameter measurement. 


That wasn’t so bad, was it?


I skipped a few steps. For a complete set of instructions check out the attached PDF at the bottom of this blog post.


For other getting started topics, check out our video playlist: