Adaptivity figures of merit and K-rail diagrams - comprehensive performance characterization of low-noise amplifiers and voltage-controlled oscillators

Generally, analog RF front-end circuits are designed to be functional under the most stringent, fixed, operating conditions, where all the performance parameters are set by crude hardware design in a fixed way. The figures of merit, resulting from such a design approach, related to only one operating condition and to only one design point, are the already existing, standard or fixed figures of merit. However, the fact that the conditions under which the RF circuits are supposed to be functional are not fixed but rather variant, must be taken into account in both the design of front-end circuits and the characterization of their performances. Accordingly, the figures of merit referring not only to one, but to a set of operating conditions and set of design points are named adaptivity figures of merit. For that purpose, K-rail diagrams are introduced in this paper, offering the possibility for an all-round performance characterization of both adaptive voltage-controlled oscillators and adaptive low-noise amplifiers. The introduced K-rail diagrams give an explicit qualitative explanation of all the existing relations and trade-offs among RF front-end circuit performance parameters such as voltage swing, tank conductance, power consumption, phase noise and loop gain of oscillators as well as noise figure, linearity, gain and power consumption of amplifiers.