Comprehensive and Macrospin-Based Magnetic Tunnel Junction Spin Torque Oscillator Model - Part I: Analytical Model of the MTJ STO

TL;DR

This paper introduces a comprehensive macrospin-based analytical model for magnetic tunnel junction spin torque oscillators, enabling efficient system-level simulations and design validation for various applications.

Contribution

It presents a new compact analytical model based on macrospin approximation, suitable for hardware description languages, and verified against experimental data for different MTJ STOs.

Findings

Model accurately matches measured data across different conditions.

Suitable for implementation in Verilog-A for system-level simulations.

Enables efficient design and analysis of MTJ STO-based circuits.

Abstract

Magnetic tunnel junction (MTJ) spin torque oscillators (STO) have shown the potential to be used in a wide range of microwave and sensing applications. To evaluate potential uses of MTJ STO technology in various applications, an analytical model that can capture MTJ STO's characteristics, while enabling system- and circuit-level designs, is of great importance. An analytical model based on macrospin approximation is necessary for these designs since it allows implementation in hardware description languages. This paper presents a new macrospin-based, comprehensive and compact MTJ STO model, which can be used for various MTJ STOs to estimate the performance of MTJ STOs together with their application-specific integrated circuits. To adequately present the complete model, this paper is divided into two parts. In Part I, the analytical model is introduced and verified by comparing it against measured data of three different MTJ STOs, varying the angle and magnitude of the magnetic field, as well as the DC biasing current. The proposed analytical model is suitable for being implemented in Verilog-A and used for efficient simulations at device-, circuit- and system-levels. In Part II, the full Verilog-A implementation of the analytical model with accurate phase noise generation is presented and verified by simulations.