Closed Loop Gain

Before we discuss the closed-loop gain, let’s review a concept: transfer function. A transfer function is a mathematical representation of the relation between the input and output of a system.

The transfer function of a closed-loop configuration is G=A/(1+βA), which is the closed-loop gain. Where A is open loop gain, β is the feedback factor, and βA is the loop gain. It is easy to see the difference between closed loop gain and open loop gain.