A Brief Guide to Nonlinear Simulations of Marki Microwave Devices in ADS

The MMIC platform stands as a cornerstone in modern microwave design, offering a versatile foundation for the development of high-performance RF components, as well as high-fidelity models. At Marki Microwave, we take full advantage of this capability during both the design phase, enabling first-pass success, and post-release to provide customers with highly accurate models. This ensures effective simulation and seamless integration into even the most complex systems for nonlinear devices that cannot be modeled by simple s-parameters. It is at this juncture that our fully nonlinear device models come into play since they allow for highly accurate simulations of mixers, multipliers, NLTLs and more!

Running these simulations can be a bit tricky, so we released a thorough tutorial on how to run all of the most common simulations which can be accessed here: https://markimicrowave.com/technical-resources/multimedia/webinars/optimal-simulation-techniques-for-high-linearity-systems/

This webinar uses Microwave Office as our simulation platform, however we have released PDKs compatible with MWO as well as ADS. In our commitment to providing comprehensive support, we've equipped our ADS PDK with a dedicated test bench, featuring pre-configured simulations for the most common parameters you may want to investigate. While the premade test benches offer convenience, we have received feedback from customers that an explicit guide on how to use the ADS PDK and how to access these premade test benches would be a valuable point of reference.

1.      Downloading the PDK

To begin a simulation, we must first download the PDK. This is achieved by navigating to the Marki Microwave home page -> Technical Resources -> Device Models, or by clicking the following link: https://markimicrowave.com/technical-resources/device-models/

Once on this page, simply click the ‘Download ADS Kit’ box to begin the download. This will download a zip file containing the PDK which can be moved to a known location on your computer.

2.      Unarchiving the PDK

With the PDK downloaded and saved to your PC, the next step is to unarchive the 7zads file you just downloaded. You do this by opening ADS and selecting File -> Unarchive and selecting the 7zads file.   This allows you to now open the pre-built workspaces.

3.      Accessing pre-built workspace

Once you have the workspace unarchived, you can go to ‘Folder View’ and see the pre-built workspace we created for ADS with most of the common measurements people want to run.

4.      The workspace

Let us look at one of the more complicated workspaces and see what is included. For this, I will simply click on the Mixer Verification_DOWN workspace to see all the most common simulations for a mixer as a downconverter. Below is a screenshot of the workspace and all the pre-created plots! This is just one example for a downconverter mixer, but there are workspaces for IP3, LO sensitivity, and more in the same file you downloaded!

5.      Customizing your measurements

Once you have selected the proper workspace for the simulation you want to run you simply edit the frequency plan and swap out the mixer. We can do this rather simply. Starting on the same workspace window, navigate to the ‘Equations’ tab at the bottom which will show you the equations that generate all of the spurs.

Customizing the measurement from here is simple since the heavy lifting of setting up the measurements is handled for you. You can use the above equations as a template to set up your own spur measurements. All you need to do is ensure that you use the same variable names in your schematic as what is shown here or change the names here to match your schematic. Either way will work just fine. To see what the variable names are in the schematic, simply navigate back to the home page and select the down arrow next to the template. This will allow you to access the schematic.

It is here that you can view and edit the variable names, edit the frequency plan and also swap out the mixer for any mixer in the PDK:

By following this brief guide, you should be well equipped to run nearly any simulation you want on virtually any mixer in our catalog. The same general steps will be taken for simulating any IQ mixer, multiplier, or NLTL in the PDK thanks to our pre-built ADS workspaces. The nonlinear device models greatly simplify the component selection and design process by providing designers with high quality simulation early in the design phase. For any questions or inquiries, reach out to our support team at [email protected]. We're here to help you with your simulation and design every step of the way!