The Effects of a Decoupling Capacitor

This topic explains how to check the difference of impedance, depending on whether a decoupling capacitor is present.

1. In the PI/EMI Analysis Heatmap dialog, select Any and set the range to "0" - “7".

2. Changing the Color scale settings changes the colors of the displayed result, as shown below.

3. Disable the fitted states for decoupling capacitors as follows.
4. In the PI/EMI Analysis module, select the Classification view, Component tab.
5. Click on the columns for C110, C114 and C116 to deselect their check boxes.

4. On the toolbar, click PI Analysis to perform the PI analysis again.

 

 

5. Select the Power Bus view, PI Distribution tab.
6. Recreate the impedance map at 66 MHz for VCC_GND, as follows.
7. Select VCC_GND in the Filter list.
8. Select the row for 66.000 MHz, and click  Generate impedance distribution for selected frequencies.

7. Click Yes to display the results of the analysis.

8. In the Impedance Distribution Heatmap dialog, configure the same settings that you specified in the Checking Impedance Distribution topic.
9. On the canvas in eCADSTAR PCB Editor, confirm that the distribution has changed.

10. Select File > Close in the PI/EMI Analysis Heatmap dialog.

 

This task is demonstrated in the following video.