Page 1 :
Where,, , ¢ Tis the transfer function or overall gain of negative feedback control system., ¢ Gis the open loop gain, which is function of frequency., ¢ His the gain of feedback path, which is function of frequency., , The derivation of the above transfer function is present in later chapters., , Effects of Feedback, , Let us now understand the effects of feedback., , Effect of Feedback on Overall Gain, « From Equation 2, we can say that the overall gain of negative feedback closed loop, control system is the ratio of 'G' and (1+GH). So, the overall gain may increase or, decrease depending on the value of (1+GH)., , «If the value of (1+GH) is less than 1, then the overall gain increases. In this case, 'GH', value is negative because the gain of the feedback path is negative., , «If the value of (1+GH) is greater than 1, then the overall gain decreases. In this case,, 'GH' value is positive because the gain of the feedback path is positive., , In general, 'G' and 'H' are functions of frequency. So, the feedback will increase the overall, gain of the system in one frequency range and decrease in the other frequency range.