Western Digital (fremont), Inc.

Read Rite Corporation

Qiuqun Qi

Xizeng Shi

Matthew R Gibbons

An MRAM storage device includes temperature dependent current sources that adjust their outputs as temperature varies. Temperature dependent current sources include one or more diodes connected to a transistor. As temperature varies so does the voltage drop across the diodes. In addition, the MRAM data storage device includes at least one digit line, at least one bit line, and at least one MRAM cell disposed proximate to a junction of a digit line and a bit line. Each end of each digit line is connected to temperature dependent current sources and current sinks. One end of each bit line is connected to a temperature dependent current source while the other end of each bit line is connected to a current sink. Two logic signals R and D are used to activate a write operation and determine the direction of the write current in the digit line.

Temperature dependent write current source for magnetic tunnel junction MRAM

A reference cell circuit for a magnetic tunnel junction MRAM includes a first magnetic tunnel junction device set to a low resistance state and a second magnetic tunnel junction device set to a high resistance state. A reference cell series unit includes the first magnetic tunnel junction device electrically coupled in series with the second magnetic tunnel junction device. The reference cell series unit further has a first end and a second end with the first end being electrically coupled to a first current source and the second end being electrically coupled to a current sink and a second current source.

Designs of reference cells for magnetic tunnel junction (MTJ) MRAM

A reference cell circuit for a magnetic tunnel junction MRAM includes two magnetic tunnel junctions where one is always set to a low resistance state and the other is always set to a high resistance state. The two magnetic tunnel junctions are connected between two segments of a bit line. The reference cell also includes a digit line that crosses both of the bit line segments.

A method and system for providing and using a magnetic memory including magnetic memory cells is disclosed. The method and system include providing a magnetic tunneling junction including a first ferromagnetic layer, a second ferromagnetic layer and an insulating layer between the first ferromagnetic layer and the second ferromagnetic layer. The magnetic memory cell is coupled to a merged word line and a bit line. The merged word line selects the magnetic memory cell during a reading and carries a write current for the magnetic memory cell during writing. The bit line provides current to the magnetic memory cell during the reading and the writing. The currents provided by the bit line and the merged word line during writing allow data to be written to the magnetic memory cell.

MRAM memory array having merged word lines

An MRAM data storage device has at least one digit line, at least one bit line, and at least one MRAM cell disposed proximate to a digit line and electrically connected to a bit line. Each end of each digit line is connected to a write current source and a write current sink. One end of each bit line is connected to a write current source and a read current source while the other end of each bit line is connected to a write current sink. Two logic signals R and D are used to determine the direction of the write current in the digit line, to select between the read current and the write current in the bit line. The state of the MRAM cell is read by detecting the voltage drop across the cell when a read current is applied.

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Fremont, CA, United States of America

Qiuqun Qi