Method of writing to a spin torque magnetic random access memory

摘要

Circuitry and methods provide an increased tunnel barrier endurance (lifetime) previously shortened by dielectric breakdown by providing a charging pulses of opposite polarity in comparison with write pulses. The charging pulse of opposite polarity may comprise equal or different width and amplitude than that of the write pulse, may be applied with each write pulse or a series of write pulses, and may be applied prior to or subsequent to the write pulse. A register is also used to keep track of the read pulse polarity such that read pulses of alternating polarity can be used in reading operations.

主权项

1. A method of accessing a magnetoresistive bit, comprising:
applying a first read pulse having a first polarity to the magnetoresistive bit, wherein each read pulse is used in evaluating a bit state for the magnetoresistive bit; recording the first polarity in a register; and after recording the first polarity in the register:
applying a second read pulse to the magnetoresistive bit, wherein a second polarity for the second read pulse is determined based on the first polarity recorded in the register, wherein the second polarity is opposite the first polarity; andrecording the second polarity in the register.