Contents
Are ground planes necessary?
A solid ground plane provides some degree of protection against electromagnetic interference (both radiated and received). I wouldn’t rely on a ground plane to solve all of your EMI problems, especially if you have components on both sides of the board; a carefully designed conductive enclosure would be more effective.
Does my PCB need a ground plane?
Most PCB designers will swear by using a ground plane, and this is certainly the best choice when working with high speed/high frequency signals. Nearly every board that includes multiple components will simply not have enough room for routing return traces alongside all signal traces.
What is the purpose of a ground plane?
The Ground Plane Because its principal purpose is to allow the flow of return current (Fig. 2.21), there should be a minimum of interruptions to it, and for this reason ground planes are more successful on a multilayer board where an entire layer can be devoted, one to the power plane and one to the ground.
What are the purpose and function of the ground plane?
In telecommunication, a ground plane is a flat or nearly flat horizontal conducting surface that serves as part of an antenna, to reflect the radio waves from the other antenna elements. The plane does not necessarily have to be connected to ground.
How does a counterpoise work?
The counterpoise functions as one plate of a large capacitor, with the conductive layers in the earth as the other plate. Since the radio frequency alternating currents from the transmitter can pass through a capacitor, the counterpoise functions as a low-resistance ground connection.
Does a ground plane have to be flat?
Why do you need a separate ground plane for analog circuitry?
The digital ground plane in the board will be busy with all of the digital signal return paths as well as filtering the power spikes created by rapidly-switching high-speed digital parts. All of this activity can create a lot of interference for your analog circuitry, so the best thing to do is to create a separate ground plane.
Why are two planes on an analog PCB important?
It is also important that these two planes do not overlap with each other, as that could cause capacitive coupling of noise from the digital ground into the analog. By carefully placing your components, you can establish regions for your separate circuitry that will allow you to not overlap your planes.
Why are analog circuits more difficult to design?
Due to the on/off nature of a digital signal, there can be more margin for error in how they are transmitted, whereas the value of an analog signal must be precisely controlled for transmission and reception. This precision is why analog circuitry can be more difficult to design than digital.
Do you need separate ground supplies for analog and digital?
This particular problem can often be avoided by having separate power supplies (and, thus, separate ground returns) for the various portions of the circuit. For example, separate analog and digital supplies with separate analog and digital grounds, joined at the star point, are common in mixed-signal applications.