Time-Domain Analysis of RF and Microwave Autonomous Circuits by Vector Fitting-Based Approach
This work presents a new method for the analysis of RF and microwave autonomous circuits directly in the time-domain, which is the most effective approach at simulation level to evaluate nonlinear phenomena. For RF and microwave autonomous circuits, time-domain simulations usually experiment convergence problems or numerical inaccuracies due to the presence of distributed elements, preventing de-facto their use. The proposed solution is based on the Vector Fitting algorithm applied directly at circuit level. A case study relative to a RF hybrid oscillator is presented for practical demonstration and evaluation of performance reliability of the proposed method.
It is shown in this paper that : 1) The Minimum Variance Self Tuning Regulators and a configuration of Adaptive Controllers with Implicit (or Explicit) Reference Model feature an asymptotic duality character which extends the duality existing in the linear case with known parameters between the minimum variance control and the modal control. 2) Adaptive Control with an Explicit Reference Model is equivalent to an Adaptive Control with an Implicit Reference Model using an intermediate adaptive predictor, if the adaptive predictor plus the control behave like the explicit reference model. 3) The result of 1) is generalized by considering the asymptotic duality between Model Reference Adaptive Controllers and the class of Stochastic self Tuning Regulators which contains the self tuning minimum variance regulator as a particular case.