Follow along with the video below to see how to install our site as a web app on your home screen.
Note: This feature may not be available in some browsers.
Normal
I always flooded my layouts with ground, and it's 100% effective until it isn't. . Adding a ground flood adds a capacitor to ground of a few pF's to every trace on the board. Most of the time, it doesn't matter, but it should be a deliberate decision, especially if you have high impedance nets that you are using to form filters.As an example: you have a 220k feedback resistor bypassed with a 100pF cap, used in a LPF tuned to 7.2kHz. 10pF parasitic capacitance on a long trace over a ground plane could shift the frequency down almost 800Hz!At a high level, ground should follow signal, and you should consider the layout as a differential input of your source/signal voltage and ground. As I said, in this design, it may not make much difference, but doing it in this way minimizes problems.
I always flooded my layouts with ground, and it's 100% effective until it isn't. . Adding a ground flood adds a capacitor to ground of a few pF's to every trace on the board. Most of the time, it doesn't matter, but it should be a deliberate decision, especially if you have high impedance nets that you are using to form filters.
As an example: you have a 220k feedback resistor bypassed with a 100pF cap, used in a LPF tuned to 7.2kHz. 10pF parasitic capacitance on a long trace over a ground plane could shift the frequency down almost 800Hz!
At a high level, ground should follow signal, and you should consider the layout as a differential input of your source/signal voltage and ground. As I said, in this design, it may not make much difference, but doing it in this way minimizes problems.
