+ Post New Thread
Results 1 to 6 of 6
  1. #1
    Member level 3
    Points: 659, Level: 5

    Join Date
    Jan 2018
    Posts
    64
    Helped
    2 / 2
    Points
    659
    Level
    5

    Ground plane in audio amplifier?

    Hello, a question: can a ground plane, create problems in power audio amplifiers?

    Example: if touching the input with the tip of whatever, the amplifier oscillates, can it be the fault of the ground plane? (Which is on both layers, bottom and top) Or is it because the amplifier is unstable?

    •   AltAdvertisement

        
       

  2. #2
    Advanced Member level 5
    Points: 24,498, Level: 38
    barry's Avatar
    Join Date
    Mar 2005
    Location
    California, USA
    Posts
    4,703
    Helped
    1038 / 1038
    Points
    24,498
    Level
    38

    Re: Ground plane in audio amplifier?

    The amplifier is obviously unstable. But is it because of the plane? Perhaps the additional capacitance of the plane is the problem. You need to analyze the circuit a little more closely, considering the plane caoacitance.


    1 members found this post helpful.

    •   AltAdvertisement

        
       

  3. #3
    Member level 3
    Points: 659, Level: 5

    Join Date
    Jan 2018
    Posts
    64
    Helped
    2 / 2
    Points
    659
    Level
    5

    Re: Ground plane in audio amplifier?

    Quote Originally Posted by barry View Post
    The amplifier is obviously unstable. But is it because of the plane? Perhaps the additional capacitance of the plane is the problem. You need to analyze the circuit a little more closely, considering the plane caoacitance.
    Thank you for the answer.



    •   AltAdvertisement

        
       

  4. #4
    Newbie level 3
    Points: 598, Level: 5

    Join Date
    Oct 2016
    Location
    TURKEY
    Posts
    3
    Helped
    0 / 0
    Points
    598
    Level
    5

    Re: Ground plane in audio amplifier?

    What is your amplifier IC , grounding method is important
    ex: star grounding



  5. #5
    Super Moderator
    Points: 79,067, Level: 68
    Achievements:
    7 years registered
    Awards:
    Most Frequent Poster 3rd Helpful Member

    Join Date
    Apr 2014
    Posts
    16,051
    Helped
    3635 / 3635
    Points
    79,067
    Level
    68

    Re: Ground plane in audio amplifier?

    Hi,

    can it be the fault of the ground plane? (Which is on both layers, bottom and top)
    Many unexperienced people "fill" the spaces between traces and think this now is a GND layer. But it is not!
    From the electrical view, a GND layer needs to be a low impedance ... thus a GND layer should be solid, without any traces in this layer.
    Only if you really know what you do .. you may insert some traces at uncritical areas. .. or split the GND plane.

    Low Impedance:
    Don´t mix it with "low ohmic".
    * low ohmic is a "DC" value. It mainly is the copper resitance between two points. Thicker and wider traces will reduce resitance.
    * but "low impedance" is an AC value. (You know that an amplifier does not oscillate with DC frequency ). Unfortunately wider, or thicker traces, or copper filled areas do not necessarily reduce impedance that much.

    Klaus
    Please don´t contact me via PM, because there is no time to respond to them. No friend requests. Thank you.


    1 members found this post helpful.

    •   AltAdvertisement

        
       

  6. #6
    Super Moderator
    Points: 29,856, Level: 42
    andre_teprom's Avatar
    Join Date
    Nov 2006
    Location
    Brazil
    Posts
    8,914
    Helped
    1128 / 1128
    Points
    29,856
    Level
    42
    Blog Entries
    9

    Re: Ground plane in audio amplifier?

    if touching the input with the tip of whatever, the amplifier oscillates
    it is likely being not self oscillation as you think, but rather a bare injection of EMI ( e.g , from mains ) through your fingers.
    --------------------------------------------------------------------------------------------------
    Part of the world that you live in, You are the part that you're giving ( Renaissance )


    1 members found this post helpful.

--[[ ]]--