Abstract: A system includes a memory array having pattern cells and data cells. The pattern cells are configured to store only a first logic state. The data cells are configured to store the first logic state or a second logic state. Bias circuitry is configured to apply voltages to the pattern cells and data cells. Sensing circuitry is configured to read the pattern cells. A controller is configured to apply, using the bias circuitry, first voltages to the pattern cells; determine, using the sensing circuitry, that at least a portion of the pattern cells switch; determine, based on the portion of the pattern cells that switch, to refresh a codeword; and apply, using the bias circuitry, the refresh of the codeword.

Abstract: Systems, methods, and apparatus for a memory device that uses multiple groups of pattern cells to select a voltage for reading memory cells. In one approach, a controller applies different magnitude levels of voltages to each of the groups of pattern cells. The controller determines which of the groups have pattern cells that first switch (e.g., switch at the lowest magnitude of applied voltage). Based on identifying the first group to switch, the controller selects a read voltage. The selected read voltage is used to read data cells (e.g., corresponding to a codeword).