Design methods for the stabilization of nonlinear circuits in large-signal regime

The dissertation presents a nonlinear approach for stability analysis. Based on the Conversion Matrix, this design method allows the enforcement of stable operations in nonlinear circuits under large-signal drive, or the intentional generation of unstable spurious signals. the Conversion Matrix approach has been implemented in commercial CAD software for practical circuit design. Different instabilities are also analyzed in a large-signal operating regime by combining the Conversion Matrix approach with other simulation techniques such as and envelope-transient and bifurcation detection tools, like auxiliary generator and pole-zero identification. These instabilities are predicted, analyzed, and finally eliminated in a global manner of operation, using the stability analysis techniques. The frequency division by two has been deeply investigated and a design procedure that allows the direct design of spurious-free circuits, or of intentionally unstable circuits like frequency dividers is explained. The design procedure based on the use of the Conversion Matrix has been extended and applied to the design of spurious free power amplifier, frequency divider and autonomous circuits like oscillators. This dissertation also presents a intensive stability analyses for oscillation startup in the transient and steady-state solutions. The technique is experimentally verified by the design of a power amplifier. Criteria for the evaluation of the critical loads that give rise to spurious frequencies are given, also defining the region for stable operation respect to circuit parameters of interest. In this way, a direct modification of the passive networks in a nonlinear circuit under large signal drive, for the removal (or introduction, if desired) of spurious frequencies appearing at high input power is allowed, without the need of random optimization procedures or numerical iterative methods.