Tuning Variables

One of the most powerful features of Genesys is real-time tuning of values in variables. You can use tuned variables almost anywhere in Genesys, including schematics, netlists, substrates, and port impedances. See almost any Genesys example for tuned variables.

Every variable in a part is tunable. You can tune the values in one variable or multiple variables. Genesys lets you dynamically tune variables to determine whether your circuit meets its requirements. You can do this by entering different values for a specific variable and simultaneously viewing the response in a graph. Continue adjusting values and viewing the graph until you get the response you want.

To make a variable tunable

Double-click a part on the schematic, this will bring up the Properties dialog.
Click the Parameters tab.
Click the Tune check box.
Click OK
Or
From the Tune window Item menu , choose Select Variables... from the drop down. This will give you a comprehensive list of everything that can be tuned.
Check the boxes for the variables that you would like tuned.
Click OK. Notice that the parameter(s) to be tuned has now changed color on the schematic and appears in the Tune window. To tune this parameter you just need to click the up/down arrows in the Value column.

To make a variable tunable in multiple parts in a schematic

Hold down the shift key while clicking the parts.
Select Schematic > Make Components Tunable from the main window. Notice that the parameter to be tuned has now changed color on the sc
- Rearrange your screen so that it looks like this:
- Make C1.C tunable
  There are multiple ways to make the value of C1 tunable.
  - Double-click C1 and click the Tune checkbox for the value.
  - Click C1 to select it, then select Make Components Tunable from the Schematic menu.
  - In the Tune Window click the Item Menu button and select Select Variables. Find C1.C and check it on.
  - Once C1 is tunable, the C=1000 pf line should turn teal-colored and the Tune Window should now have a C1.C entry. All of the analyses turn red because the schematic has changed.

Only calculate the linear analysis

In the Tune Window only enable the Linear Analysis and the S21 graph by clicking the Analysis and Graph dropdown buttons, as seen below.

Tune the C1.C value

Finally tune the C1.C value by clicking in the grid box where it says 1000 then, either,

roll the mouse-wheel to tune up or down
Click the up/down arrows in the grid box to move up or down
Type a new value and press enter

After typing a new C value of 1500 and pressing enter we see the following display. The dark red is the original simulation result S21. The bright red is the new tuned simulation result. Note that the graph range was changed to 0...10 for slightly better readability.

Save your workspace

This is always a good idea. Saved workspaces remember what you were tuning and what runs when you tune. Click the save button (the diskette icon in the main toolbar) to save.

Specifying Tuning Options

Select analyses to run during the tune

Click the Analyses button in the Tune Window and check on/off the analyses you want to run while tuning. This includes most evaluations (sweeps, optimizations) as well. The menu goes away when you click off the menu area.
Check Use All Autocalc to have the list be all analyses set to Automatically Recalculate. The list then dynamically changes to match the set of analyses that are Automatically Recalculate. This is similar to the way GENESYS2004 worked.

Select graphs to checkpoint when you save a setting

Click the Graph checkpoint button in the Tune Window and check on/off the graphs you want to checkpoint when you checkpoint a named setting. The menu goes away when you click off the menu area.
Check Use All Visible to have the list be all visible graphs. The list dynamically changes as you open and close graphs.

Selecting which values are tuned up/down

There are three options regarding the allowable set of values for tuned variables:

Normal – This option is unrestricted. For lumped elements, such as resistors and capacitors, values between zero (0) and infinity are possible. You can use this option to determine the theoretical optimum values.
Multiple – This option uses parameter values, which are integer multiples of the value in the Value column. For example, if the value equals 0.5, then the allowable values are 0.5, 1.0, 1.5, and so on.
Standard – This option uses only common values, such as 1.2, 3.3, 4.7, 5.6, and so on for lumped elements. The tuning percentage is shown in the first box in the Value column. This controls the amount values are stepped when tuning.

To specify tuning options:

Click the first box in the Variable column in the Tune window.
Select an option from the list.

Adjusting the Value of Tuning Options

The tuning percentage controls the amount values are stepped when tuning. Whenever a variable is tuned up or down, a tuning ratio is used to calculate the new value. You can use the Tune window to adjust the Normal and Standard options by percentages. The Multiple option uses decimal values for adjusting.

To adjust the value of a tuning option:

Type a new value in the Value box for the variable you want.
Click the up or down arrow to increase or decrease the tuning ratio.*
You can press F6 to decrease or F7 to increase the tuning percentage by a factor of 2.

Setting Tuned Values

You can set tuned values in a couple of ways. Begin by selecting the value you want to change (click in the grid box for the value), then

Scroll the mousewheel:

Scroll up and down to tune the value up and down.

Click the scroll arrows:

Click the up arrow to increase the value, the down arrow to decrease the value.

Type a value and press the enter key:

Type a value, and when you press the enter key it will be entered and the analyses you've selected run.

When values have been set and you want to save a set under a new name just type the name into the name entry field and click the save settings (diskette) icon. Click the graph checkpoint button to create a named checkpoint.

Reverting Tuned Values

Genesys lets you revert to your original values if you do not want the newly tuned values.

To revert to previous values:

Click the Use These Settings button and select from a named set. The set named Original is the original settings.

Checkpoints

A checkpoint is a saved intermediate point. In a graph it is usually a trace showing potentially good values.

To establish checkpoints in a graphed analyses:

Select Show Named Settings from the Item menu in the Tune window. This will bring up a field to type names/settings in.
Type a name into the Named Setting entry field (such as Better ).
Click the Checkpoint button

As you tune you will see an echo left behind of the original settings, this is the checkpoint. You can add as many checkpoints as you like. Each new checkpoint will have a different color, as in the Gain/Return Loss traces below.

To remove all checkpoint traces from all graphs:

Click the Remove Checkpoint button in the tune window. This will remove checkpoints from the graphs listed in your graph checkpoint list. As you then tune a checkpoint will not be created.

Gang Tuning

Another common task in tuning is to tune more than one parameter at the same time. This is called Gang Tuning and the easiest way to do it is with an equation variable. In the following figure an equation variable for the Capacitor Q named qt has been setup.

By selecting the equation from the workspace tree you can see the details of the variable.

The variable qsub is defined with a ?6, which makes it tuneable. The variable qt is defined as qsub to the 10th power which will tune in an exponential form.

Genesys 2008.07