non-inverting mode Op Amp noise

Discussion in 'General Electronics Chat' started by screen1988, May 31, 2013.

  1. screen1988

    Thread Starter Member

    Mar 7, 2013
    310
    3
    I am reading about non-inverting mode Op Amp.
    [​IMG]
    Here is part that I am confused. Can you explain more?
    On the other end of the spectrum,if the resistor values (RF, RG) are too high, there is an increase in noise and the susceptibility to parasitic capacitances, which can also limit bandwidth and possibly cause instability and oscillation
     
  2. crutschow

    Expert

    Mar 14, 2008
    12,991
    3,227
    Resistor thermal voltage noise is proportional to the resistance so high value resistors can have noise comparable to or larger than that of the op amp, which increases the total noise.

    If the resistor values are high enough to be comparable to the reactive impedance of stray capacitance within the bandwidth of the op amp circuit, such as from the (-) input to ground, then peaking or instability in the response can occur.
     
  3. GopherT

    AAC Fanatic!

    Nov 23, 2012
    5,991
    3,742
    Google "Johnson noise".
     
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