Computationally Efficient Innovative Techniques for the Design-Oriented Simulation of Free-Running and Driven Microwave Oscillators

Analysis techniques for injection-locked oscillators/amplifiers (ILO) can be broadly divided into two classes. To the first class belong methods with a strong and rigorous theoretical basis, that can be applied to rather general circuits/systems but which are very cumbersome and/or time-consuming to apply. To the second class belong methods which are very simple and fast to apply, but either lack of validity/accuracy or are applicable only to very simple or particular cases. In this thesis, a novel method is proposed which aims at combining the rigorousness and broad applicability characterizing the first class of analysis techniques above cited with the simplicity and computational efficiency of the second class. The method relies in the combination of perturbation-refined techniques with a fundamental frequency system approach in the dynamical complex envelope domain. This permits to derive an approximate, but first-order exact, differential model of the phase-locked system useable for the steady-state, transient and stability analysis of ILOs belonging to the rather broad (and rigorously identified) class of nonlinear oscillators considered. The hybrid (analytical-numerical) nature of the formulation developed is suited for coping with all ILO design steps, from initial dimensioning (exploiting, e.g., the simplified semi-analytical expressions stemming from a low-level injection operation assumption) to accurate prediction (and fine-tuning, if required) of critical performances under high-injection signal operation. The proposed application examples, covering realistically modeled low- and high-order ILOs of both reflection and transmission type, illustrate the importance of having at one's disposal a simulation/design tool fully accounting for the deviation observed, appreciable for instance in the locking bandwidth of high-frequency circuits with respect to the simplified treatments usually applied, for a quick arrangement, in ILO design optimization procedures.