Circuit Conditions for Parametric Amplification
L. B. Valdes · Journal of Electronics and Control · 1958
It is shown that signals may be amplified in a circuit which consists exclusively of passive elements if a non-linear or a time-varying reactance is present. Emphasis is placed on describing the physical model which makes amplification possible and the circuit conditions which must be satisfied. The differences between parametric amplifiers and mixers or modulators are discussed.