Distortion cancellation in 3-D non-volatile memory
A method in a memory that includes multiple analog memory cells arranged in a three-dimensional (3-D) configuration, includes identifying multiple groups of potentially-interfering memory cells that potentially cause interference to a group of target memory cells. Partial distortion components, which are inflicted by the respective groups of the potentially-interfering memory cells on the target memory cells, are estimated. The partial distortion components are progressively accumulated so as to produce an estimated composite distortion affecting the target memory cells, while retaining only the composite distortion and not the partial distortion components. The target memory cells are read, and the interference in the target memory cells is canceled based on the estimated composite distortion.
1. A method, comprising:
in a memory, which comprises multiple memory cells arranged in a three-dimensional (3-D) configuration, identifying multiple groups of potentially-interfering memory cells that potentially cause interference to a group of target memory cells;
estimating partial distortion components, which are inflicted by the respective groups of the potentially-interfering memory cells on the target memory cells;
progressively accumulating the partial distortion components so as to produce an estimated composite distortion affecting the target memory cells, while retaining only the composite distortion and not the partial distortion components;
quantizing the partial distortion components; and
reading the target memory cells; and
canceling the interference in the target memory cells based on the estimated composite distortion.
2. The method according to claim 1 , wherein accumulating the partial distortion components comprises discarding each partial distortion component after accumulating the partial distortion component into the estimated composite distortion.
3. The method according to claim 1 , wherein accumulating the partial distortion components comprises storing the estimated composite distortion in a cache memory having a size that is independent of a number of the groups of the potentially-interfering memory cells.
4. The method according to claim 1 , wherein accumulating the partial distortion components comprises summing the partial distortion components.
5. The method according to claim 1 , further comprising quantizing the estimated composite distortion using non-uniform quantization.
6. An apparatus, comprising:
an interface, which is configured to communicate with a memory that comprises multiple memory cells arranged in a three-dimensional (3-D) configuration; and
storage circuitry, which is configured to:
identify multiple groups of potentially-interfering memory cells that potentially cause interference to a group of target memory cells;
estimate partial distortion components, which are inflicted by the respective groups of the potentially-interfering memory cells on the target memory cells;
progressively accumulate the partial distortion components so as to produce an estimated composite distortion affecting the target memory cells, while retaining only the composite distortion and not the partial distortion components;
quantize the partial distortion components;
read the target memory cells; and
cancel the interference in the target memory cells based on the estimated composite distortion.
7. The apparatus according to claim 6 , wherein the storage circuitry is further configured to discard each partial distortion component after accumulating the partial distortion component into the estimated composite distortion.
8. The apparatus according to claim 6 , wherein the storage circuitry is further configured to store the estimated composite distortion in a cache memory having a size that is independent of a number of the groups of the potentially-interfering memory cells.
9. The apparatus according to claim 6 , wherein the storage circuitry is further configured to accumulate the partial distortion components by summing the partial distortion components.
10. The apparatus according to claim 6 , wherein the storage circuitry is further configured to quantize the estimated composite distortion using non-uniform quantization.
11. An apparatus, comprising:
a memory comprising multiple memory cells arranged in a three-dimensional (3-D) configuration; and
storage circuitry configured to:
identify multiple groups of potentially-interfering memory cells that potentially cause interference to a group of target memory cells;
estimate partial distortion components, which are inflicted by the respective groups of the potentially-interfering memory cells on the target memory cells;
progressively accumulate the partial distortion components so as to produce an estimated composite distortion affecting the target memory cells, while retaining only the composite distortion and not the partial distortion components;
quantize the partial distortion components;
read the target memory cells; and
cancel the interference in the target memory cells based on the estimated composite distortion.
12. The apparatus according to claim 11 , wherein the storage circuitry is further configured to discard each partial distortion component after accumulating the partial distortion component into the estimated composite distortion.
13. The apparatus according to claim 11 , wherein the storage circuitry is further configured to store the estimated composite distortion in a cache memory having a size that is independent of a number of the groups of the potentially-interfering memory cells.