Abstract: A magnetic sensor for identifying small superparamagnetic particles bonded to a substrate contains a regular orthogonal array of MTJ cells formed beneath that substrate. A magnetic field imposed on the particle, perpendicular to the substrate, induces a magnetic field that has a component within the MTJ cells that is along the plane of the MTJ free layer. If that free layer has a low switching threshold, the induced field of the particle will create resistance changes in a group of MTJ cells that lie beneath it. These resistance changes will be distributed in a characteristic formation or signature that will indicate the presence of the particle. If the particle's field is insufficient to produce the free layer switching, then a biasing field can be added in the direction of the hard axis and the combination of this field and the induced field allows the presence of the particle to be determined.

Abstract: An SMT MRAM device includes a plurality of SMT MRAM cells arranged in an array of rows and columns. Single bit lines connect the columns of the SMT MRAM cells for receiving an in-phase data signal. Source lines connect pairs of rows of the SMT MRAM cells for receiving an out-of-phase data signal. Out-of-phase switching devices are connected to the source lines for selectively transferring the out-of-phase signal to the at least one source lines. Column select transistors are connected to the single bit lines for transferring an in-phase data signal to a selected column of the SMT MRAM cells. A precharge circuit selectively charges or discharges the single bit lines. Ground switching devices selectively connect to the source lines to a ground reference voltage source. A method for programming a selected SMT MRAM cell within a provided SMT MRAM device is described.

Abstract: Magnetic memory elements such as Phase Change RAM and Spin Moment Transfer MRAM require high programming currents. These high programming currents require high gate to source/drain voltages for the cell transistors controlling these programming currents, which can degrade the reliability of these cell transistors. This invention describes a circuit and method to write information into individual memory cells while minimizing the gate voltage stress in the cell transistors of the memory cells in which no information is being written. The circuit of this invention has a separately controllable word line voltage supply for each row of the memory array and a separately controllable voltage supply for each bit line of the memory array. During the write operation the voltage is raised for the word line of only one row of the array. The bit line voltages are then adjusted so that a 1 is written into the desired cells in that row and a 0 is written into the desired cells in that row.

Abstract: This invention describes a circuit and method to limit the stress caused by gate voltages required to write a one or zero in magnetic memory elements using the Giant magneto-resistive effect, such as Phase Change RAM and Spin Moment Transfer MRAM, sometimes referred to as Spin Torque Transfer MRAM, which require high programming currents. The circuit and method selects one cell at a time for writing a one or a zero, different voltages to write a one or a zero, and a precharge circuit to limit the stress on non selected cells.

Abstract: A data scrubbing apparatus corrects disturb data errors occurring in an array of memory cells such as SMT MRAM cells. The data scrubbing apparatus receives an error indication that an error has occurred during a read operation of a grouping of memory cells within the array of memory cells. The data scrubbing apparatus may generate an address describing the location of the memory cells to be scrubbed. The data scrubbing apparatus then commands the array of memory cells to write back the corrected data. Based on a scrub threshold value, the data scrubbing apparatus writes the corrected data back after a specific number of errors. The data scrubbing apparatus may further suspend writing back during a writing of data. The data scrubbing apparatus provides a busy indicator externally during a write back of corrected data.

Abstract: A gate voltage boosting circuit provides a voltage boost to a gate of a select switching MOS transistor of a spin-torque MRAM cell to prevent a programming current reduction through an MTJ device of the spin-torque MRAM cell. A spin-torque MRAM cell array is composed of spin-torque MRAM cells that include a MTJ element and a select switching device. A local word line is associated with one row of the plurality of spin-torque MRAM cells and is connected to a gate terminal of the select switching devices of the row of MRAM cells to control activation and deactivation. One gate voltage boosting circuit is placed between an associated global word line and an associated local word line. The gate voltage boosting circuits boost a voltage of a gate of the selected switching device during writing of a logical “1” to the MTJ element of a selected spin-torque MRAM cell.

Abstract: A spin-torque MRAM array has MRAM cells arranged in rows and columns. Bit lines are connected to each of the MRAM cells on each column. Source select lines are connected to each MRAM cell of a pair of rows and are oriented orthogonally to the bit lines. Write lines are connected to the gate of the gating MOS transistor of each MRAM cell of the rows. The MRAM cells are written in a two step process with selected MRAM cells written to a first logic level (0) in a first step and selected MRAM cells written to a second logic level (1) in a second step. A second embodiment of the spin-torque MRAM array has the bit lines commonly connected together to receive the data and the source select lines commonly connected together to receive an inverse of the data for writing.

Abstract: We describe a reference cell structure for determining data storing cell resistances in an SMT (spin moment transfer) MTJ (magnetic tunneling junction) MRAM array by comparing data cell currents with those of the reference cell. Since the reference cell also utilizes spin moment transfer (SMT) magnetic tunneling junction (MTJ) cells, there would ordinarily be the danger that the act of reading the reference cell could change its magnetization orientations and be a source of error for subsequent comparisons. Therefore the present invention describes a new circuit arrangement for the reference cell that directs read currents through two SMT MTJ cells in opposite directions so that the transfer of spin moments cannot affect the relative magnetization directions of the cells.

Abstract: An SMT MRAM device includes a plurality of SMT MRAM cells arranged in an array of rows and columns. Single bit lines connect the columns of the SMT MRAM cells for receiving an in-phase data signal. Source lines connect pairs of rows of the SMT MRAM cells for receiving an out-of-phase data signal. Out-of-phase switching devices are connected to the source lines for selectively transferring the out-of-phase signal to the at least one source lines. Column select transistors are connected to the single bit lines for transferring an in-phase data signal to a selected column of the SMT MRAM cells. A precharge circuit selectively charges or discharges the single bit lines. Ground switching devices selectively connect to the source lines to a ground reference voltage source. A method for programming a selected SMT MRAM cell within a provided SMT MRAM device is described.

Abstract: A gate voltage boosting circuit provides a voltage boost to a gate of a select switching MOS transistor of a spin-torque MRAM cell to prevent a programming current reduction through an MTJ device of the spin-torque MRAM cell. A spin-torque MRAM cell array is composed of spin-torque MRAM cells that include a MTJ element and a select switching device. A local word line is associated with one row of the plurality of spin-torque MRAM cells and is connected to a gate terminal of the select switching devices of the row of MRAM cells to control activation and deactivation. One gate voltage boosting circuit is placed between an associated global word line and an associated local word line. The gate voltage boosting circuits boost a voltage of a gate of the selected switching device during writing of a logical “1” to the MTJ element of a selected spin-torque MRAM cell.

Abstract: Systems and methods for a SSD controller enabling data transfer between a host and flash memories have been achieved. A major component of the SSD controller is a non-volatile buffer memory, which interfaces fast disk drive protocols and slow write and read cycles of NAND flash. Preferably MRAM or Phase Change RAM can be used for the buffer memory. Non-volatile tables can also be implemented for storing dynamic logical to physical address translation, defective sector information and their spare sectors and/or SSD configuration parameters.

Abstract: Systems and methods for a PC or server architecture have been disclosed. The architecture is characterized by using non-volatile RAM modules, such as MRAM modules, for at least a part of the main memory, thus accelerating the power-on sequence of the computer. Components, which were stored in prior art either in battery backed CMOS Modules or in flash memory have been deployed in the non-volatile part of the main memory. Such components can be power-on self test codes, system configuration information, device drivers, a portion of the Operating system, and a portion or all of application programs and related application data.

Abstract: Voltage and current stress for magnetic random access memory (MRAM) cells can weed out potential early failure cells. Method and circuit implementation of such a stress test for a MRAM comprise coupling a stress test circuit to the read bus of the MRAM and stressing the Magnetic Tunnel Junctions (MTJS) by tying them to ground by activating isolation transistors associated with them. Read word lines control which MTJs are stressed Both the method and implementation can be used for any memory cells based on resistance differences, such as Phase RAM or Spin Valve MRAM.

Abstract: A magnetic sensor for identifying small superparamagnetic particles bonded to a substrate contains a regular orthogonal array of MTJ cells formed beneath that substrate. A magnetic field imposed on the particle, perpendicular to the substrate, induces a magnetic field that has a component within the MTJ cells that is along the plane of the MTJ free layer. If that free layer has a low switching threshold, the induced field of the particle will create resistance changes in a group of MTJ cells that lie beneath it. These resistance changes will be distributed in a characteristic formation or signature that will indicate the presence of the particle. If the particle's field is insufficient to produce the free layer switching, then a biasing field can be added in the direction of the hard axis and the combination of this field and the induced field allows the presence of the particle to be determined.

Abstract: Voltage and current stress for magnetic random access memory (MRAM) cells can weed out potential early failure cells. Method and circuit implementation of such a stress test for a MRAM comprise coupling a stress test circuit to the read bus of the MRAM and stressing the Magnetic Tunnel Junctions (MTJS) by tying them to ground by activating isolation transistors associated with them. Read word lines control which MTJs are stressed Both the method and implementation can be used for any memory cells based on resistance differences, such as Phase RAM or Spin Valve MRAM.

Abstract: A gate voltage boosting circuit provides a voltage boost to a gate of a select switching MOS transistor of a spin-torque MRAM cell to prevent a programming current reduction through an MTJ device of the spin-torque MRAM cell. A spin-torque MRAM cell array is composed of spin-torque MRAM cells that include a MTJ element and a select switching device. A local word line is associated with one row of the plurality of spin-torque MRAM cells and is connected to a gate terminal of the select switching devices of the row of MRAM cells to control activation and deactivation. One gate voltage boosting circuit is placed between an associated global word line and an associated local word line. The gate voltage boosting circuits boost a voltage of a gate of the selected switching device during writing of a logical “1” to the MTJ element of a selected spin-torque MRAM cell.

Abstract: An MRAM reference cell sub-array provides a mid-point reference current to sense amplifiers. The MRAM reference cell sub-array has MRAM cells arranged in rows and columns. Bit lines are associated with each column of the sub-array. A coupling connects the bit lines of pairs of the columns together at a location proximally to the sense amplifiers. The MRAM cells of a first of the pair of columns are programmed to a first magneto-resistive state and the MRAM cells of a second of the pair of columns are programmed to a second magneto-resistive state. When one row of data MRAM cells is selected for reading, a row of paired MRAM reference cells are placed in parallel to generate the mid-point reference current for sensing. The MRAM reference sub-array may be programmed electrically or aided by a magnetic field. A method for verifying programming of the MRAM reference sub-array is discussed.

Abstract: An MRAM array has a plurality of MRAM devices that are arranged in rows and columns with segmented word lines. A magnetic biasing field is coupled to each of the MRAM devices. The MRAM devices are programmed by providing a bidirectional bit line current to a selected bit line of the plurality of bit lines and a word line current pulse to one word line segment of one row of word line segments by discharging coupled word line segments. The field biasing device may be permanent magnetic layers or write biasing lines in proximity to the fixed magnetic layer of each of the MRAM and has a magnetic orientation equivalent to the magnetic orientation of a word line segment magnetic field generated by the word line current pulse.

Abstract: A spin-torque MRAM array has MRAM cells arranged in rows and columns. Bit lines are connected to each of the MRAM cells on each column. Source select lines are connected to each MRAM cell of a pair of rows and are oriented orthogonally to the bit lines. Write lines are connected to the gate of the gating MOS transistor of each MRAM cell of the rows. The MRAM cells are written in a two step process with selected MRAM cells written to a first logic level (0) in a first step and selected MRAM cells written to a second logic level (1) in a second step. A second embodiment of the spin-torque MRAM array has the bit lines commonly connected together to receive the data and the source select lines commonly connected together to receive an inverse of the data for writing.

Abstract: Magnetic Random Access Memory (MRAM) can be programmed and read as fast as Static Random Access Memory (SRAM) and has the non-volatile characteristics of electrically eraseable programmable read only memory (EEPROM), FLASH EEPROM or one-time-programmable (OTP) EPROM. Due to the randomness of manufacturing process, the magnetic tunnel junctions (MTJ) in MRAM cells will require different row and column current combinations to program and not to disturb the other cells. Based on adaptive current sources for programming, this disclosure teaches methods, designs, test algorithms and manufacturing flows for generating EEPROM, FLASH EEPROM or OTP EPROM like memories from MRAM.