Lexicon Mass

In an electrical circuit, the ground is usually the common reference point for the measured Voltages. Mentally, the mass is understood as a conductive body, which is everywhere on the same electrical potential. The term "mass" suggests an extended, heavy and inert body, which is actually the case in practice. In vehicles, for example, the metal Chassis and the sheet metal body is usually used as electrical mass. In hi-fi equipment, the Case is also often part of the mass.

The idea that every point of the ground is at the same electrical potential is convenient, but unfortunately not always correct. Since currents can flow in the ground, potential differences can also occur, and in certain cases this can have undesirable consequences for the operation of the electronic circuit, such as the coupling of interference signals. One therefore tries to limit the paths that such currents can take. For this purpose, one separates the uniform mass into different masses, which are either not connected to each other at all, or only via a single, exactly defined line. The different masses partly have their own names, depending on the purpose they serve:

• The signal ground is the reference point for the Useful signals within the circuit. Interference currents should not be able to flow in the signal ground if possible.
• The housing ground is the return point for interference currents caused by external radiation. In addition to the device housing itself, this often includes the shielding of connectors and connected cables.

The analog ground is the reference point for analog signals in mixed analog/digital devices. The digital ground is the reference point for the digital signals in mixed analog/digital devices.

Depending on the device, the ground can be internally fanned out and structured even further, always with the aim of separating the path taken by the individual currents in it as far as possible.

See also:

• Wikipedia article: Ground (electronics)