Injection locking of a spin transfer nano-oscillator, based on an in-plane magnetized magnetic tunnel junction and generating the frequency f0, to an external signal of varying frequency fe is studied experimentally and with macrospin simulations. It is shown, that if the driving signal has the form of a microwave current, the locking effect is well-pronounced near fe≅2f0, but is almost completely absent near fe≅f0, confirming predictions of analytical theory. It is also shown that noise plays an important role in the locking process, causing the linewidth of the locked oscillation to substantially exceed that of the driving signal.

Abstract-The design of systems defined as networks (interconnections) of identical subsystems emerges as an interesting engineering problem, with some open issues. One of these issues is how to "retune" the interconnection in order to ensure the stability and the performance of the system. Based on the LFT representation and on the input-output framework, we propose in this paper some efficient "retuning" methods using convex optimization involving LMI constraints. The proposed approach can be interpreted as an extension of usual state space methods. Its application is investigated for the design of a network of PLLs.

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