Microprocessor based projects external circuitry

Discussion in 'General Electronics Chat' started by saleemsm, May 15, 2006.

  1. saleemsm

    Thread Starter Active Member

    May 15, 2006
    36
    0
    The Xtal circuit uses high impedance input buffer made by CMOS. Such
    high impedance is easy to pickup noise through capacitive
    coupling,

    we can reduce it by using low impedance copper path making it
    known as guard ring.

    We can see this also in the high resistant
    non-inverting amplifier built by opamp circuit.


    my question is:

    1. what is the guard ring that is being talked about?
    2. where is it seen in the high resistant non - inv amp in opamp circuit.
     
  2. n9352527

    AAC Fanatic!

    Oct 14, 2005
    1,198
    4
    It's just a pcb track surrounding the high-impedance sensitive node. It is usually kept at the same potential as the sensitive node, or driven at the same potential with low impedance. Thus it would sink the stray currents away from the sensitive node.

    An example is, for non-inverting op-amp the guard ring is usually connected to the negative (inverting input) and physically surrounds the positive (non-inverting input)
     
  3. saleemsm

    Thread Starter Active Member

    May 15, 2006
    36
    0

    thanks for the answer.

    I am starting a project and need help in getting started.
     
  4. n9352527

    AAC Fanatic!

    Oct 14, 2005
    1,198
    4
    If you need further help, just start a new thread and explain what you need. Preferably in details and be specific to maximise the chance of getting answers. Good luck with your project.
     
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