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Accurate modeling of magnetic tunnel junction (MTJ) is critical for design of memories such as spin-transfer-torque magnetoresistive random access memory (STT-MRAM) and spin logic circuits such as spin flip flops. This paper reviews several static and dynamic models for the MTJ and compares them for their capabilities and limitations. Furthermore, a Verilog-A model is developed to predict dynamic characteristics of the MTJ. These models are used in simulating a prototype circuit to illustrate their strengths and weaknesses. [ABSTRACT FROM AUTHOR]

Dynamic average-value models (AVMs) for AC-DC rectifier circuits are generally formulated in state-space form and hence are straightforward to implement in state-variable-based simulation languages. In the nodal analysis-based approach used in electromagnetic transient (EMTP-type) simulation packages, the development of AVMs requires additional effort to reformulate and interface the models with the external ac and dc networks. This paper proposes a new averaged-circuit model for three-phase line-commutated rectifiers which is directly interfaced with the ac and dc networks, thereby achieving a simultaneous solution of the respective variables in EMTP-type solution. The proposed model is verified against conventionally interfaced model, as well as detailed switching model of the original rectifier circuit. A significant improvement of numerical accuracy and stability of the solution is demonstrated even at fairly large time steps. [ABSTRACT FROM AUTHOR]