Multi-bit cell read-out techniques for MRAM cells with mixed pinned magnetization orientations

A memory device comprising:

• a Multi-Bit Cell (MBC) coupled between a bit line and a source line, wherein the MBC includes a first MTJ element, a second MTJ element and a selector coupled in series, wherein the first and second MTJ elements have different low-resistance levels and different high-resistance levels, and wherein the first and second MTJ elements have opposite pinned magnetization polarization orientations;
• one or more memory circuits configured to;
• sense a first sense voltage of the MBC;
• program the MBC using a first program voltage after sensing the first sense voltage, wherein the first MTJ element will be in a known state after programming;
• sense a second sense voltage of the MBC after programming the MBC using the first program voltage;
• compare the second sense voltage to the first sense voltage, after sensing the second sense voltage, to determine a first resistance change state;
• program the MBC using a second program voltage after sensing the second sense voltage, wherein the state of the first MTJ element will be flipped;
• sense a third sense voltage of the MBC after programming the MBC using the second program voltage;
• compare the third sense voltage to the second sense voltage, after sensing the third sense voltage, to determine a second resistance changed state;
• and
• determine a read state of the MBC based on the first resistance change state and the second resistance change state.

A method comprising:

• sensing a first instance of state parameter of a Multi-Bit Cell (MBC), wherein the MBC includes a first and a second cell element having different sets of state parameter values and having different pinned magnetization polarizations;
• programming the MBC using a first set of state programming conditions after sensing the first state parameter value, wherein the first cell element will be in a first state after programming;
• sensing a second instance of the state parameter of the MBC after programming the MBC using the first set of state programming conditions;
• comparing the second instance of the state parameter to the first instance of the state parameter, to determine a first state change result;
• programming the MBC using a second set of state programming conditions after sensing the second instance of the state parameter, wherein the first cell element will be in a second state after programming;
• sensing a third instance of the state parameter of the MBC after programming the MBC using the second set of state programming conditions;
• comparing the third instance of the state parameter to the second instance of the state parameter, to determine a second state change result;
• and
• outputting a read state of the MBC based on the first state change result and the second state change result.

A method of reading from an array of Multi-Bit Cells (MBCs) comprising:

• receiving a read command for a selected plurality of MBCs in the army of MBCs, wherein the MBCs each include a first and second MTJ coupled in series and having opposite pinned magnetization polarizations;
• sequentially applying a first and second switching condition to the selected plurality of MBCs, wherein a state of the first MTJ of each selected MBC flips after the second switching condition with respect to the state of the first MTJ after the first switching condition;
• determining for each selected MBC, after applying each switching condition, whether a state of the MBCs have changed;
• and
• determining for each selected MBC, a read state of the MBCs based on whether or not the state of the MBCs changed in response to each applied switching condition.