Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

OP-amp and transistor

  1. Sep 1, 2011 #1
    What is the meaning of differential gain?
    Iam studying a document that says, opamp can provide differential gain unlike transistor. I don,t know what does it mean. Can some clear me out.

    More, what is meant by bias volatge in case of op-amp. I am very beginer to electronics.
     
  2. jcsd
  3. Sep 1, 2011 #2
    Differential gain means that your op-amp's output is related to the difference between it's positive and negative inputs.

    So if you had an differential amplifier with a gain of 1 and applied +5V to the + input and +3V to the - input you would get a +2V output.


    Bias voltage on an op-amp is the output value with no inputs applied to the op-amp. Generally it will be about zero but you can construct your circuit so that it has a different value.
     
  4. Sep 1, 2011 #3

    berkeman

    User Avatar

    Staff: Mentor

    The input of most opamps uses a differential transistor gain stage, and there are more gain stages after that. So you get high effective differential gain with opamps -- the output is a function of the difference of the two inputs, multiplied by a very large number.

    http://en.wikipedia.org/wiki/Opamp

    The bias voltages on an opamp are the input quiescent voltages. You will generally set the bias voltage at the + terminal explicitly, and use negative feedback to set the bias voltage at the - terminal.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: OP-amp and transistor
  1. Op Amps (Replies: 8)

  2. Op amps (Replies: 4)

Loading...