In this section, let’s take a look at what Parametric Sub-Circuits in ADS are. This tool can be used to create reusable and adjustable circuit modules. These sub-circuits can achieve different circuit functions and performances by setting different parameter values.

We open the previous TestBench:

In this schematic, we have a subcircuit X1. We select X1 and click to view its internal structure.

We can see that there are two variable parameters in the subcircuit. We need to declare them in the top-level design and then use them in the subcircuit. This requires switching back and forth, which is troublesome. We can make the parameterized subcircuit more convenient to use with some simple steps.

For demonstration, let’s open schematic_withQ in Design1.

We want to be able to pass and change the values ​​of these components directly in the top-level design. Select “File -Design Parameters”.

Then we open the “Cell Parameters” window. We set the Parameter Name to “L1”, then select Real (real number, Complex, Integer, String) for Value Type, 41 for Default Value, and Unitless () for Parameter Type/Unit, which means we don’t consider the unit when using the parameter. Then click “Add”:

Similarly, we define another variable “C1”, set the default value to “22”, and then click “Add”. In this example, we add these two parameters. In actual design, you can define them according to your own needs. Then click “Save AEL file” and “OK” to save the set parameters.

Then, we apply the defined parameters to the subcircuit.

Then we save the subcircuit, return to the main design, and switch the subcircuit to schematic_withQ, but no parameters are displayed under Symbol at this time:

We delete it, and then drag the modified schematic_withQ symbol directly from the workspace into the top-level design. We can see that the parameters just defined are displayed below:

We disable the variable we defined previously:

Then perform a simulation. Then in the main design, we click on Tuning and select L1 and C1. Let’s save the initial settings first:

Then we adjust these two parameters to get the real-time frequency response (exiting directly will not modify the original value):

We can also use parameter nesting, define a var, and then assign it to the parameter of the subcircuit:

At this point, parameters can be passed between them.

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