Analysis of the stability of oscillation modes in parallel-running oscillators

All of the oscillation modes existing in a parallel-running oscillator system consisting of several oscillators with identical Rieke diagrams are extracted and their stability is studied. It is shown that single-mode oscillation can be easily obtained if the operating point of the desired mode is located at a point away from the origin of the Rieke diagram and the operating points of other modes are at the origin. In this case the operating points of different unwanted modes are necessarily found at points away from the origin and these modes may be stable. However, they are not detrimental in the multiple oscillator system. Analysis and experiments are performed for three representative parallel-running systems using hybrid elements.