7.1 Preliminaries of Dynamical Systems7.1.1 Introduction to Stability Analysis of Nonlinear Dynamical Systems7.1.2 Equilibrium Point7.1.3 Periodic Steady State7.1.4 Lyapunov Exponents7.2 Bifurcations of Nonlinear Dynamical Systems7.2.1 Bifurcations of Equilibrium Points7.2.2 Bifurcations of Periodic Orbits7.3 The Averaging Method and Multiple Time Scales7.4 Averaging Theory in Coupled Oscillator Systems7.5 Obtaining the Parameters of the van der Pol Oscillator Model7.6 An Alternative Perturbation Model for Coupled-Oscillator Systems7.7 Matrix Equations for the Steady State and Stability Analysis7.8 A Comparison between the Two Perturbation Models for Coupled Oscillator Systems7.9 Externally Injection-Locked COAs7.10 Phase Noise7.11 Modulation7.12 Coupled Phase-Locked Loops7.13 Conclusion