Partition of non-volatile memory array to reduce bit line capacitance
View Patent ↗The present invention that partitions a memory array in N segments by switchably partitioning the bit lines in the array. In the exemplary embodiment, a top set of sense amps control the even bit lines and a bottom set of sense amps control the odd bit lines. The segmentation transistors turn on or off depending on the selected word line location in the array. Since bit line capacitance is mainly from the metal bit line to bit line coupling to their immediate neighbors, the bit line neighbors in the partitioned array are floating in some segments of the bit lines. The overall bit line capacitance is significantly reduced with a negligible increase in die size, resulting in reduced sensing times and enhanced read and write performance.
1. A non-volatile memory comprising:
an array of memory storage units formed into a plurality of columns;
a plurality of bit lines corresponding to each of the columns, wherein the memory storage units of a given column are connectable to the corresponding bit line;
a plurality of sense circuits each connectable to one or more bit lines whereby the data content of memory storage units connected to a corresponding connected bit line can be sensed; and
at least one switch formed on each of said bit lines for the partition thereof into a first portion that remains connectable to the corresponding sense circuit and second portion not connectable to the corresponding sense circuit,
wherein the bit lines are orderable as alternating odd and even bit lines, the sense circuits connectable to the odd bit lines formed along a first side of the array and the sense circuits connectable to the even bit lines formed along the side of the array opposite to the first side, wherein said switches partition the array into a plurality of segment, and wherein between each pair of adjacent segments of the array are situated in an alternating manner one of either a switch on each of said even bits lines controlled by a common select line or a switch on each of said odd bits lines controlled by a common select line.
2. The non-volatile memory of claim 1 , wherein said bit lines are global bit lines.
3. The non-volatile memory of claim 2 , wherein said columns are each composed of a plurality of strings of memory cells having a NAND type architecture, each of the strings connectable to the corresponding global bit line.
4. The non-volatile memory of claim 1 , wherein said bit lines are implemented in metal.
5. The non-volatile memory of claim 1 , wherein said switches are implemented as transistors.
6. The non-volatile memory of claim 1 , wherein said switches partition the array into a plurality of segments.
7. A method of operating a non-volatile memory array, comprising:
selecting a word line to access;
determining to which of a plurality of array partitions the selected word line belongs; and
floating alternate bit lines in one or more of the array partitions other than that to which the selected word line belongs, wherein said floating alternate bit lines comprises:
setting one of either a switch value on the odd bit lines or a switch value on the even bit lines between each of said partitions.
8. A non-volatile memory of comprising:
an array of memory storage units formed into a plurality of columns and rows;
a plurality of bit lines corresponding to each of the columns, wherein the memory storage units of a given column are connectable to the corresponding bit line;
a plurality of sense circuits each connectable to one or more bit lines whereby the data content of memory storage units connected to a corresponding connected bit line can be sensed;
a plurality of word lines corresponding to each of the rows; and
circuitry to selectively partition said bit lines, whereby alternate bit lines in one or more of the array partitions other than that to which the selected word line belongs can be floated, wherein the circuitry to selectively partition said bit lines includes at least one switch formed on each of either the even ones of said bit lines or the odd ones of said bit lines and bit line in those portions of the array partition other than that to which a selected word line belongs are floated by setting a switch value between each of said partitions on all of said bit lines.