On the effect of time delays in negative feedback amplifiers

Time delays are intrinsic to all existing devices and circuits. For the majority of applications, time delays are so small that their effects can be disregarded. However, when considering feedback amplifiers, depending on open-loop poles and loop gain, the effect of a small time delay inside the feedback path may turn out to be of considerable importance. This paper analyzes the frequency response effects associated with time delays in feedback amplifiers, exploiting these effects to achieve bandwidth enhancements. An illustration of this effect is presented using a TL082 in series-shunt configuration, attaining 100% bandwidth extension, when associated with a 36 m length RG58 coaxial cable as delay element.