Method of connection between Analog & Digital ground with noise protection.

[moreaniruddha]

I am Going to design Power supply for analog & digital circuits. Now I want to connect the ground of Digital & Analog power supply. But as per my past experience with these circuits, I got Noise problems, when I connect these ground directly to each other. I also try to connect these ground through Inductor, but this technique not minimizes the noise from circuit. If any one know the solution to protect both ground from each other but we connect it. Please kindly reply to this post.
here, I want to mention I have seen EMIGUARD like product of Murata Manufacturing Co. Ltd. also three terminal capacitor. But I am not used these products. If any one know about these products, please guide me, how to use these products?

 

[gavin23]

I also use inductors to connect analog and digital grounds. Specifically I use ferrite beads. Is this what you're using and still having problems with?

-Gavin

 

[Gundam001]

I am Going to design Power supply for analog & digital circuits. Now I want to connect the ground of Digital & Analog power supply. But as per my past experience with these circuits, I got Noise problems, when I connect these ground directly to each other. I also try to connect these ground through Inductor, but this technique not minimizes the noise from circuit. If any one know the solution to protect both ground from each other but we connect it. Please kindly reply to this post.
here, I want to mention I have seen EMIGUARD like product of Murata Manufacturing Co. Ltd. also three terminal capacitor. But I am not used these products. If any one know about these products, please guide me, how to use these products?

Hello,

There different approach in connecting the analog and digital ground in different applications.

For example for power supply (AC to DC) Switch mode, the termination for both analog and digital should be in the negative terminal of the bulk capacitor for the primary side and for the secondary side it should be in the first filter capacitor after the diode. Planing is not a good idea for both analog and digital ground. Star termination is better.

For embedded system is also different. The used of ferrite beads is one approach, but these create split plane on the ground plane. The best approach is to group the circuit between analog and digital with a common ground plane below it.
If split plane cannot be avoided, use bypass capacitors to shorten the ground loop..

Anyway there are a lot of things can be done to improve signal integrity and noise immunity.

MODERATOR ACTION: Signature link is removed

 

[scanman]

Hi,

This article may be helpful.

Grounding of Mixes Signal Systems

scanman

 

[moreaniruddha]

I also use inductors to connect analog and digital grounds. Specifically I use ferrite beads. Is this what you're using and still having problems with?

-Gavin

I used resistor type 1 mH inductor in my circuit & also try for wire wound inductor.