Using Datasheet Values

Discussion in 'General Electronics Chat' started by crazyengineer, Jan 10, 2012.

  1. crazyengineer

    Thread Starter Member

    Dec 29, 2010
    Okay, so I have been using ideal op amp models to figure out the gain of my op amp circuits. However, I want to figure out the real gain of my op amp circuits but to do that, I need the large signal voltage gain. However, on most datasheets they have different values such as min,typical, and maximum.

    When looking at different parts datasheets, should I take in the min,typical, or maximum values in my designs?
  2. PaulEE


    Dec 23, 2011
    If by voltage gain you mean "large signal open loop gain", you can ignore this in most typical op-amp applications.

    Since the open loop gain is so high, the feedback equation (which I've derived in another thread) ends up getting simplified such that the feedback resistors are the devices that govern the final gain of your particular circuit.

  3. Adjuster

    Well-Known Member

    Dec 26, 2010
    Generally, adequate performance can be obtained by using devices with sufficient minimum gain, in a configuration designed to cope with the likely gain variation. Negative feedback is often used to minimise the effect of device gain variations. If the system gain is sufficiently below that of the basic amplifier, moderate device gain changes will have little effect.

    Similarly, the DC working point of a transistor may be stabilised by feedback. Different procedures have been proposed using the typical gain or the minimum as a starting point for the design, but preferably the working point should be checked at both ends of the range. Transistors are often shown with fixed bias in elementary examples or simple hobbyist circuits. This can work under certain circumstances, but in many cases it will not be satisfactory.