SENSE uses its powerful solver to perform parasitic Capacitance extraction on any
touch sensor design.
SENSE follows the method that is described in detail in Maxwell Capacitance Matrix, to perform the necessary simulations and extract the Capacitance values of a sensor.
SENSE enables you to obtain as many columns (or vectors) of the capacitance matrix as you like, so you can save time if you select not to get the full capacitance matrix. Actually, simulation time scales with the number of the selected "active" conductors. For example, if the simulation of one vector takes 10 minutes, then the simulation of 10 vectors will take approximately 100 minutes.
You can do this selection by choosing only the conductors you are interested in testing. For example, in the screen shown below, if you want to find out the performance only on the bottom part of the screen, you simply need to choose the bottom electrode.
Since all capacitance values for this electrode will be simulated, there is no need to choose other electrodes (for example the vertical ones that define the different nodes).
SENSE will print all the mutual capacitance values towards this electrode and its self capacitance in a table format, as shown below:
In case you want to speed up the simulation or pin point the performance on a specific area, SENSE allows you to Crop the Layout by drawing a selection box so that only the cropped part of the geometry will be taken into consideration for the simulation.
Simply draw the box, Click DONE and then Click Next.
PRO TIP: Although this process can save lots of time and resources, you should pay special attention when cropping the layout to create a new realistic layout
Reading the capacitance results in SENSE is a simple task. First you need to go to the Results screen, where you have three selection boxes.
The first one is the No Pointer and Pointer selection. Here you decide which capacitance results you want to view, i.e. with the Pointer in a specific Placement or without a Pointer.
The second one is the Type of results that will appear in front of you. It can be Capacitance in pF, Change of Capacitance (ΔC) in pF or the Change of Capacitance (ΔC/C) in relation to the no pointer capacitance in % (those last two are only active when a Pointer selection is chosen in the first box).
The third one is the Selection of the Active conductor. This means that you will view capacitances in relation to the selected conductor.
Now, the view of the results is done by navigating with your cursor over the sensor inside the Canvas or by navigating over the Capacitance results column on the right hand side.
The conductor highlighted with yellow is the selected (active) one.
By navigating or left clicking over another conductor or over the column, conductors will be highlighted with an orange colour. Those values represent the mutual capacitance of the active conductor towards another conductor. They can be either important mutual capacitances, for example in PCAPs or parasitic capacitances you want to avoid.
By navigating or left clicking over the selected conductor, it also gets highlighted. This represents the self capacitance.
Finally, by clicking the “Show Heatmap” box, the sensor is coloured with warm and cold colours to visualise the high or low capacitance of each conductor.