You can use the Equivalent Circuit Analysis when you want to get the equivalent circuit of the whole touch sensor as a netlist. This netlist, that may also include finger touch, can be further used in the Counts Analysis (System), where the sensor is connected with the controller. You may also download the netlist and use it as input in any spice tool.
First click on Physical Analysis => Create a New Analysis => Equivalent Circuit Analysis. Here you see a stepper on top the screen that guides you through the process that you must follow:
- Assign Terminals
Terminals represent the electrical connection between the sensor and the controller. So, here you must define the points of the layout that will be later on used as connection points, included the shielding parts and also the ground where the lumped elements, like resistors and capacitors, will be connected.
In the following example of a design including four buttons, we select as terminals:
- the edges of the traces and two curves of each pad nearby where the resistor will be connected,
- two curves of the shielding and two curves of their nearby pads where the two sampling capacitors will be connected.
- one curve in the middle of the shielding where the ground pin of the controller (Vss) will be connected.
So, finally 19 terminals have been selected in the above example.
You must select each terminal one by one. Otherwise multiple curves that belong to the same surface and have been selected altogether (with Ctrl + left click) will be regarded as parts of the same terminal.
For further details about proper terminal selection for each case, please see also the "Walkthrough to get Counts".
2. Add a Pointer
Here you select the pointer and the pointer placements on top of the sensor, to evaluate the performance on the different positions. Separate netlists will be created for each pointer and/or pointer placements.
3. Analysis Options
Here you first select resources to be used for this analysis. Choosing more CPU will result in faster simulations and using more memory will result in supporting larger and more complex layouts. For more details on this please see "Resources in SENSE".
By activating the "Advanced options" you may choose between "High Accuracy" and "High Speed" options or you may define the accuracy level of your choice.
In the final step you check that everything is ok and click "Run Analysis".
Once the analysis is completed, all the netlists of each combination (touch sensor + pointer placement) are listed here. These netlist can now be downloaded and used as input in any SPICE simulator or loaded in SENSE's System section for a Counts Analysis after selecting a specific controller.