MULTI-LEVEL MEMORY CONTROLLER WITH PROBABILITY-DISTRIBUTION-BASED ENCODING

摘要

A memory controller includes an encoder, a modulator, and a demodulator. A nonvolatile memory includes memory cells, each programmable to one of three or more levels. According to first encoded data, the modulator programs a first subset of the memory cells to a first of the levels and a second subset of the memory cells to a second of the levels. Measurable values of the first subset are characterized by a first probability density function having a first width. Measurable values of the second subset are characterized by a second probability density function having a second width. The first width is greater than the second width. The encoder generates the first encoded data based on input data such that the first subset is smaller than the second subset. The demodulator is configured to output second encoded data in response to measurable values of the memory cells.

主权项

1. A memory controller for a nonvolatile memory including a plurality of memory cells, each of the plurality of memory cells being configured to be programmed to one of a plurality of levels, the plurality of levels being greater than two, the memory controller comprising:
an encoder configured to receive input data and generate first encoded data based on the input data; a modulator configured to program the plurality of memory cells according to the first encoded data, wherein
a first subset of the plurality of memory cells is programmed to a first level of the plurality of levels,a second subset of the plurality of memory cells is programmed to a second level of the plurality of levels,measurable values of the first subset of the plurality of memory cells are characterized by a first probability density function having a first width,measurable values of the second subset of the plurality of memory cells are characterized by a second probability density function having a second width,the first width of the first probability density function is greater than the second width of the second probability density function, andthe encoder is configured to generate the first encoded data such that a quantity of the first subset of the plurality of memory cells is less than a quantity of the second subset of the plurality of memory cells; a demodulator configured to output second encoded data in response to measurable values of the plurality of memory cells; and a decoder configured to decode the second encoded data to produce decoded data.