A new field-assisted access scheme of STT-RAM with self-reference capability

Spin-transfer torque random access memory (STT-RAM) has demonstrated great potentials in embedded and stand-alone applications. However, process variations and thermal fluctuations greatly influence the operation reliability of STT-RAM and limit its scalability. In this work, we propose a new field-assisted access scheme to improve the read/write reliability and performance of STT-RAM. During read operations, an external magnetic field is applied to a magnetic tunneling junction (MTJ) device, generating a resistive sense signal without referring to other devices. Such a self-reference scheme offers a very promising alternative approach to overcome the severe cell-to-cell variations at highly scaled technology node. Furthermore, the external magnetic field can be also used to assist the MTJ switching during write operations without introducing extra hardware overhead. Simulation results show that compared to the existing self-reference scheme, our proposed design can improve the read sense margin by more than 200% and reduce the write error rate down to 2.29×10^-9.