Parameter estimation and performance optimization of voltage controlled oscillators

Abstract

The paper is focused on a useful application related to our optimization technique of the arrays of coupled oscillators at millimeter-wave frequencies, a pair of voltage-controlled oscillators coupled through a two-port passive network being treated. A distinct section of the paper is focused on a method to estimate unknown circuit parameters starting from measurements performed on the real system, the method being based on a minimization technique. Other part of the paper treats the optimization of certain performances of the system; we have chosen as objective function the phase shift of the oscillator pair, which is difficult to be adjusted in practice. We used an appropriate frequency space representation by means of the desired network function generated in full symbolic form for a linearized circuit model. This is combined with some measurements performed on the real system and a minimization algorithm for some scalar functions of multiple variables provided by Matlab Optimization Toolbox. The algorithm is suitable to compute optimal circuit parameters which guarantee the minimum respectively maximum values of the performance quantity. Linear or small-signal nonlinear circuits can be treated in this manner. The proposed optimization techniques was tested and validated with simulation data on an illustrative example.