Abstract: A sense amplifier (11) and method for sensing a MRAM cell (77) is provided. The sense amplifier (11) includes a precharge circuit (13?) having an operational amplifier (40, 42) that uses a voltage divider (115, 116) in a feedback path to control the amount of charge stored on a capacitor (104, 105). During a precharge portion of a read operation, the charge stored on the capacitor (104, 105) is used to precharge the sense amplifier (11). By using charge sharing to precharge the sense amplifier (11), the sense amplifier (11) can be precharged to a steady state common mode voltage more quickly, thus decreasing time required for a read operation.

Abstract: A magnetoresistive random access memory (MRAM) has separate read and write paths. This reduces the peripheral circuitry by not requiring switching between read and write functions on a particular line. By having the paths dedicated to either read signals or write signals, the voltage levels can be optimized for these functions. The select transistors, which are part of only the read function, may be of the low-voltage type because they do not have to receive the relatively higher voltages of the write circuitry. Similarly, the write voltages do not have to be degraded to accommodate the lower-voltage type transistors. The size of the overall memory is kept efficiently small while improving performance. The memory cells are grouped so that adjacent to groups are coupled to a common global bit line which reduces the space required for providing the capacitance-reducing group approach to memory cell selection.

Abstract: A circuit provides a stress voltage to magnetic tunnel junctions (MTJs), which comprise the storage elements of a magnetoresitive random access memory (MRAM), during an accelerated life test of the MRAM. The stress voltage is selected to provide a predetermined acceleration of aging compared to normal operation. A source follower circuit is used to apply a stress voltage to a subset of the memory cells at given point in time during the life test. The stress voltage is maintained at the desired voltage by a circuit that mocks the loading characteristics of the portion of the memory array being stressed. The result is a closely defined voltage applied to the MTJs so that the magnitude of the acceleration is well defined for all of the memory cells.