when to separate AGND from GND.

Thread Starter

ashokraj

Joined Feb 1, 2018
94
I have looked at many schematics. I have noticed that, some parts in the circuit are connected to GND, few are having AGND, some circuits(sensors) are having both the GND and AGND. Could some one please explain me what is GND and AGND and when do I need to separate them ? Also, If there is any application notes from popular semiconductors that would be a biggest help for me.

Thank you,
Ashok
 

Irving

Joined Jan 30, 2016
1,009
AGND = analog ground. Simplistically, done correctly, it keeps all the analog, low-noise, input circuitry isolated from the noisy digital/power circuits. But there are many ways to do it badly... and make things worse...

Here's some info from Analog Devices:
https://www.analog.com/en/analog-dialogue/articles/staying-well-grounded.html

From the AAC library
https://www.allaboutcircuits.com/technical-articles/an-introduction-to-ground/

From Cadence PCB Design
https://resources.pcb.cadence.com/blog/2020-the-top-5-pcb-design-guidelines-for-analog-circuits-2

Youtube
 

MaxHeadRoom

Joined Jul 18, 2013
21,405
Due to the indiscriminate usage of reference to GND, which generally makes it indiscernible from other ground references, you need to qualify it.
e.g. Earth GND, Chassis GND etc
 
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