Content addressable memory for large search words
AssigneeMacronix International Co., Ltd.
InventorHang-Ting Lue
Life of this patent
Estimating the term…
Abstract
A memory array is arranged to store data words in respective sets of TCAM cells, where each TCAM cell is configured to store ternary states of a bit of the stored word. A circuit to select a set of TCAM cells in the set of TCAM cells, such as decoders and drivers for word lines, bit lines, block select gates. A circuit to apply an input search word to the TCAM cells in the selected set of TCAM cells, such as a search word buffer or driver on one of word lines or bit lines for the array. A circuit to generate an output indicating similarity of the stored word in the selected set of TCAM cells to the input search word, based on mismatch or possible mismatch of more than one bit of the search word.
Claims17
A memory, comprising:
- a memory array arranged to hold stored words in respective sets of content addressable memory (CAM) cells, each CAM cell configured to store states of a bit of a stored word;
- a circuit to apply an input search word to CAM cells in a selected set of CAM cells;
- and
- a circuit to generate an output indicating similarity of a stored word in the selected set of CAM cells to the input search word,
- wherein the output generated by the circuit to generate the output includes a signal indicating similarity when a number of mismatches of bits in the stored word in the selected set of CAM cells to the input search word is below a threshold, the threshold being greater than one,
- wherein the memory array comprises an array of memory cells, and each CAM cell in the sets of CAM cells including one or more memory cells of the array to store states of a bit of a stored word, and
- wherein the array of memory cells includes a plurality of bit lines coupled to respective columns of stacks of memory cells in the array, and a plurality of word lines coupled to memory cells in respective rows of stacks of memory cells in the array, and the one or more memory cells in the CAM cells in one of the sets of CAM cells are disposed in one or more levels of one of the respective rows of stacks of memory cells.
A memory, comprising:
- an array of memory cells arranged to hold stored words in respective sets of content addressable memory (CAM) cells, each CAM cell in the sets of CAM cells including one or more memory cells of the array configured to store states of a bit of a stored word;
- a circuit to apply an input search word to CAM cells in a selected set of CAM cells;
- and
- a circuit to generate an output indicating similarity of a stored word in the selected set of CAM cells to the input search word,
- wherein the output generated by the circuit to generate the output includes a signal indicating similarity when a number of mismatches of bits in the stored word in the selected set of CAM cells to the input search word is below a threshold, the threshold being greater than one, and
- wherein the array of memory cells comprises an array of stacks of AND memory cells.
A memory, comprising:
- a memory array arranged to hold stored words in respective sets of content addressable memory (CAM) cells, each CAM cell configured to store states of a bit of a stored word;
- a circuit to apply an input search word to CAM cells in a selected set of CAM cells;
- and
- a circuit to generate an output indicating similarity of a stored word in the selected set of CAM cells to the input search word,
- wherein the output generated by the circuit to generate the output includes a signal indicating similarity when a number of mismatches of bits in the stored word in the selected set of CAM cells to the input search word is below a threshold, the threshold being greater than one, and
- wherein the input search word includes a plurality of partial search words, and the circuit to generate an output indicating similarity includes logic to accumulate similarity match results of a plurality of partial search words to indicate similarity of the input search word.
Dependencies are inferred from the claim text.