Method of writing to a spin torque magnetic random access memory
A method includes destructively reading bits of a spin torque magnetic random access memory and immediately writing back the original or inverted values. A detection of the majority state of the write back bits and a conditional inversion of write back bits are employed to reduce the number of write back pulses. A subsequent write command received within a specified time or before an original write operation is commenced will cause a portion of the write back pulses or the original write operation pulses to abort. Write pulses during subsequent write operations will follow the conditional inversion determined for the write back bits during destructive read.
1. A method of reading and writing to a plurality of bits in a spin-torque magnetoresistive memory array, the method comprising:
sampling the bits in the spin-torque magnetoresistive memory array;
setting the bits to a first state in the magnetoresistive spin-torque memory array;
resampling the bits to evaluate states of the bits;
storing a value of each of the bits in one of a plurality of latches, the value being either the first state or a second state;
reading the values of the bits in the latches; and
initiating a first resetting of the bits in the spin-torque magnetoresistive memory array to the second state if a stored value for a bit was the second state in the plurality of latches.
2. The method of claim 1 further comprising:
detecting which of the first or second states of the bits is a majority immediately following the storing step; and
inverting the states written in the resetting step if the second state is detected as the majority state.
3. The method of claim 1 further comprising:
aborting the first resetting step for a portion of the plurality of bits; and
initiating a second resetting of the portion of the plurality of bits for either the first state or the second state if a subsequent write operation is received prior to completing the first resetting step.
4. The method of claim 3 further comprising:
delaying the initiation of the second resetting step if the subsequent write operation is received prior to completing the first resetting step; and
storing write operations for the portion of the plurality of the bits for subsequent writing to either the first state or the second state.
5. The method of claim 3 further comprising:
delaying the initiation of the second resetting step if the subsequent write operation is received prior to completing the first resetting step;
storing write operations; and
writing the states of multiple portions of the plurality of the bits to either the first state or the second state.
6. The method of claim 1 wherein the spin-torque memory array comprises a plurality of banks, each bank including a plurality of rows, each row including a plurality of ECC words and a plurality of inversion status bits, each ECC word including a plurality of data bits and one of a plurality of ECC or parity bits, wherein the steps are performed for each row.
7. The method of claim 6 wherein the first resetting step consists of:
resetting only the data bits in a row, and the method further comprising:
delaying the first resetting step for ECC or parity bits in the row.
8. The method of claim 6 further comprising:
generating independent write current pulses for ECC words using a write clock phase generator for each one or more ECC word.