Harmonic-balance technique for the shortening of the initial transient of microwave oscillators

Computer aided design (CAD) tools have been developed to reduce oscillator start-up times while maintaining their original features in terms of oscillation frequency or power. The tools are based on the application of pole-zero identification to the unstable solution from which the oscillation originates. The identification is combined with a harmonic-balance technique that maintains the steady-state oscillatory solution at the desired values. A technique has also been developed to eliminate spurious oscillations while maintaining the desired features of the oscillator circuit. Two different circuits are presented: a 2.4 GHz oscillator for switched operation and an unstable oscillator at 9 GHz to which the stabilization technique is applied. The experimental results have shown good agreement with the simulations.