Capacitance Extraction Using Ansys Q3D

Hello everyone, this is Adel from Ozen Engineering, and in this video, I'll show you how to extract capacitance using Ansys Q3D. For this, we will create some parallel plates. So let's start by drawing a rectangle. Here, I'll change the X size to 1.4 and the Y size to 1. 7. Click Apply. OK.

Now we need to duplicate this rectangle to create the parallel plates. So select it. To start, click Go to Edit, Duplicate Along Line, Select Corner, and set Z to 0. Click OK. Now, if I double-click on rectangle 1, we can rename it. I rename it P1, and we can change the color.

I do the same for the second rectangle. To assign copper to the created objects, let's select them. Right-click, go to Assign Boundary, and select Thin Conductor. Here, the material is set to copper; let's click OK.

The next step is to identify the nets, so let's go to the project manager, right-click on Nets, and select Auto Identify Nets. And here, you can see our nets identified. Now, to add a ground net reduced matrix, right-click on Reduce Matrix and select Ground Net.

Here, we will choose P1 and click Save and Close. This reduced matrix references the defined ground net instead of the infinite ground. Now, we need to add a solution setup, so right-click on Analysis, add Solution Setup, and let's only select Capacitance and click OK.

We can now run a validation check, so right-click on the design name and click Validation Check, then right-click on Setup One and click Analyze. The simulation completed successfully. So let's try to click on Setup One and click Matrix. Here, you can see the capacitance in pF.

Make sure you're selecting GND Matrix, and here you can see the capacitance value. Now, let's take a look at this example of a MEMS die cutout in two configurations, one with pads only and another with pads connected to RF lines.

Following the same workflow, the capacitance of the pads was extracted. Here, we can see the simulation setup. So, the thin conductor boundary condition was applied to the pads. Here, we can see our nets identified. The ground net matrix was added with the ground selected.

And we can look at the results. So here, I'll change it from original to ground net matrix. And here, we have the capacitance matrix with the self-capacitance on the diagonal and the mutual capacitance on the off-diagonal. Going back to the paths with the RF lines, let's look at the results.

Here, you can see that the RF lines introduce a small increase, but the paths are the primary contributors to the overall capacitance. This concludes this example; thanks for watching, and see you in the next video.