摘要:
A tunable reference cell scheme for magnetic random access memory (MRAM) circuitry selectively couples reference cells and data cells to shared write driver circuitry. Magnetic tunnel junctions (MTJs) in the reference cells can be programmed to a selected magnetic orientation using the shared write driver circuitry. The programmed reference cells can be merged with other programmed reference cells and/or with fixed reference cells to produce a tunable reference level for comparison with MTJ data cells during a read operation. Sharing write driver circuitry between data cells and reference cells allows programming of reference cells without consuming increased area on a chip or macro.
摘要:
Systems and methods for multiple-time programmable (MTP) devices. An MTP device includes a magnetic tunnel junction (MTJ) device programmable to a plurality of states based on voltage applied across the MTJ device. The plurality of states include a first resistance state corresponding to a first binary value stored in the MTJ device based on a first voltage, a second resistance state corresponding to a second binary value stored in the MTJ device based on a second voltage, a third resistance state corresponding to a breakdown of a barrier layer of the MTJ device based on a third voltage, and a fourth resistance state corresponding to an open fuse based on a fourth voltage.
摘要:
A Magnetic Random Access Memory (MRAM) logic circuit includes read sensing circuitry having a first level corresponding to a first category of logic circuitry and a second logic level corresponding to a second category of logic circuitry. The logic circuitry may be switchable between circuitry having the first logic level and circuitry having the second logic level according to the category of the logic circuit being implemented.
摘要:
Methods and apparatus for testing a resistive memory element are provided. In an example, an initial test resistor in a resistance network coupled to a first input of a sense amplifier is selected, where the resistive memory element is coupled to a second input of the sense amplifier and an output of the sense amplifier is measured. Another test resistor is selected based on the output of the sense amplifier and both the measuring the output step and the selecting another test resistor step are repeated until the output of the sense amplifier changes. A resistance of the resistive memory element is estimated based on the last test resistor selected, where the selected test resistors and the resistive memory element pass respective currents having substantially similar amplitudes and are coupled to respective access transistors having substantially similar properties.
摘要:
A method of establishing a reference level includes providing first and second non-overlapping paths from a first node to a second node, providing first and second reference magnetic random access memory (MRAM) elements in the first path, providing third and fourth reference MRAM elements in the second path, measuring a first value indicative of a resistance between the first node and the second node, and setting the reference level based at least in part on the measured value. Also an associated reference circuit.
摘要:
A method of generating a non-reversible state at a bitcell having a first magnetic tunnel junction (MTJ) and a second MTJ includes applying a program voltage to the first MTJ of the bitcell without applying the program voltage to the second MTJ of the bitcell. A memory device includes a bitcell having a first MTJ and a second MTJ and programming circuitry configured to generate a non-reversible state at the bitcell by applying a program signal to a selected one of the first MTJ and the second MTJ of the bitcell.
摘要:
A Magnetic Random Access Memory (MRAM) includes read sensing circuitry having an equalizer device configured between a bit cell output node and a reference node of the bit cell. The equalizer is turned on to couple the output node to the reference node during an initial portion of a read operation and to decouple the output node from the reference node after an equalization delay period. A sense amplifier is enabled to provide a data output from the bit cell only after the delay period and decoupling of the output node from the reference node to provide balanced sensing speed of data represented by parallel and antiparallel state magnetic tunnel junctions (MTJs).
摘要:
A multi-free layer magnetic tunnel junction (MTJ) cell includes a bottom electrode layer, an anti-ferromagnetic layer on the bottom electrode layer, a fixed magnetization layer on the anti-ferromagnetic layer and a barrier layer on the fixed magnetization layer. A first free magnetization layer is on a first area of the barrier layer, and a capping layer is on the first free magnetization layer. A free magnetization layer is on a second area of the barrier layer, laterally displaced from the first area, and a capping layer is on the second free magnetization layer. Optionally current switches establish a read current path including the first free magnetization layer concurrent with not establishing a read current path including the second free magnetization layer. Optionally current switches establishing a read current path including the first and second free magnetization layer.
摘要:
A flip-flop has an output control node and an isolation switch selectively couples a retention sense node to the output control node. A sense circuit selectively couples an external sense current source to the retention sense node and to magnetic tunneling junction (MTJ) elements. Optionally a write circuit selectively injects a write current through one MTJ element and then another MTJ element. Optionally, a write circuit injects a write current through a first MTJ element concurrently with injecting a write current through a second MTJ element.
摘要:
A large scale memory array includes a uniform pattern of uniformly sized dummy bit cells and active bit cells. Sub-arrays within the large scale memory array are separated by the dummy bit cells. Signal distribution circuitry is formed with a width or height corresponding to the width or height of the dummy bit cells so that the signal distribution circuitry occupies the same footprint as the dummy bit cells without disrupting the uniform pattern across the large scale array. Edge dummy cells of a similar size or larger than the standard size bit cells may be placed around the edge of the large scale array to further reduce pattern loading affects.