Open-loop gain: Difference between revisions

Revision as of 22:41, 6 January 2018

Revision as of 03:31, 14 March 2018

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The definition of open-loop gain (at a fixed frequency) is

<math>A_{\text{OL}} = \frac{V_{\text{out}}}{\left(V^+ - V^-\right)},</math>

where <math>V^ + -V^-</math> is the input voltage difference that is being amplified. The dependence on frequency is not displayed here.

== Role in non-ideal gain ==

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However, with the use of open-loop gain, the equation becomes:

<math>G = \frac{- \frac{R_2}{R_1}}{1 + \frac{ 1}{A}\frac{R_2}{R_1}}</math>

\frac{R_2}{R_1}}{A}}</math>

Notice that the equation becomes effectively the same for the ideal case as <math>A</math> approaches infinity.