Shared bit line SMT MRAM array with shunting transistors between the bit lines
View Patent ↗An array of rows and columns of SMT MRAM cells has each of the columns associated with one of its adjacent columns. Each of the SMT MRAM cells of the column is connected to a true data bit line and each of the SMT MRAM cells of the associated pair of columns is connected to a shared complement data bit line. A shunting switch device is connected between each of the true data bit lines and the shared complement data bit line for selectively connecting one of the true data bit lines to the shared complement data bit line to effectively reduce the resistance of the complement data bit line and to eliminate program disturb effects in adjacent non-selected columns of the SMT MRAM cells.
1. An array of SMT MRAM cells comprising:
paired columns of the SMT MRAM cells;
a plurality of first type bit lines, wherein each of the first type bit lines are connected to a terminal of an MTJ device of each of the SMT MRAM cells on one column of the SMT MRAM cells;
a plurality of second type bit lines, wherein each of the second type bit lines is connected to a source terminal of a gating device of each of the SMT MRAM cells on one column; and
shunting means for selectively connecting the first type bit lines with the second type bit lines of the same column to inhibit program disturbance of an unselected column of the pair of columns of the SMT MRAM cells.
2. The array of SMT MRAM cells of claim 1 wherein each of the second type bit lines is connected to the adjacent columns of SMT MRAM cells.
3. The array of SMT MRAM cells of claim 2 wherein the second type bit lines are constructed to have a width that is sufficiently wide to reduce a resistance of the second type bit line such that the array of SMT MRAM cells is larger and is more efficiently in terms of area.
4. The array of SMT MRAM cells of claim 3 wherein the width of the second type bit line is twice the width of the first type bit line.
5. The array of SMT MRAM cells of claim 1 wherein each of the columns of the SMT MRAM cells are connected to one adjacent second type bit lines of the plurality of the second type bit lines.
6. The array of SMT MRAM cells of claim 5 further comprising means for connecting the two adjacent second type bit lines in parallel to merge the two adjacent second type bit lines to appear much wider and therefore less resistive to permit a larger and more area efficient array of SMT MRAM cells.
7. The array of SMT MRAM cells of claim 1 wherein the first type bit line is a true data bit line and the second type bit line is a complement data bit line.