Transfer Properties of Single- and Coupled-Circuit Stages with and without Feedback

Universal curves of the reciprocal of the complex response function are studied for systems with one or two tuned circuits. The normalized parabola for two circuits is presented with a net of loci for the origin of co-ordinates within it. The ratio Q1/Q2, the amount of fixed detuning, the amount of coupling, and amplitude and phase of any additional feedback independently displace the origin with respect to its position in case of two identical, uncoupled circuits without feedback. Complex cases may be easily analyzed. Different methods incorporating regeneration or feedback loops are discussed which allow practical bandwidth control within wide limits.