Patent ID: 6865104

Claim:
A method of setting up a write current to be utilized in a magnetoresistive random access memory (MRAM) cell array device; said MRAM device including an array of plural memory cells, and a grid of plural conductive traces including a first array of parallel conductive traces extending in a first direction across the array of plural memory cells, and a second array of conductive traces extending in a second direction substantially perpendicular to said first direction across the array of plural memory cells, so that conductive traces of said first array and of said second array of traces intersect at particular memory cells of said array of memory cells, said device including a variable-calibration write current circuit capable of being selectively connected to a selected one of said plurality of memory cells by the particular conductive traces crossing at that selected memory cell to respectively write to and store in said selected memory cell a binary data value according to the direction of magnetization of a free magnet layer of the selected memory cell; said method including steps of: calibrating the write current circuit in a first iteration by; a) attempting to write a calibration data value to a selected memory cell utilizing an initial write current; b) sensing whether the calibration data value is successfully written to the selected memory cell; c) incrementing the write current, and d) repeating steps (a) through (c) until the calibration data is successfully written into the selected memory cell, and noting this first write current; and in a second iteration: e) further incrementing the write current; f) writing a calibration data value to a selected memory cell; g) applying the write current to a selected conductive trace; h) sensing a calibration data value written to a selected memory cell across which extends the selected conductive trace of step (g) i) repeating steps (e) through (h) until an error of calibration data is noted on step (h), and noting this second write current; determining an optimized write current based on the first and the second write currents.