Apparatus and methods for sensing hard bit and soft bits
AssigneeSanDisk 3D LLC
InventorsChang Siau, Jeffrey Koon Yee Lee, Tianhong Yan, Yingchang Chen, Gopinath Balakrishnan, Tz-yi Liu
Life of this patent
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Abstract
A method is provided for reading a memory cell of a nonvolatile memory system. The method includes generating a hard bit and N soft bits for the memory cell in a total time corresponding to a single read latency period and N+1 data transfer times.
Claims17
A method for reading a hard bit and N soft bits of a memory cell of a nonvolatile memory system in response to a single read command, the method comprising:
- generating a sense signal proportional to a current of the memory cell;
- generating a reference signal that comprises 2N+1 distinct reference signal values;
- generating a comparison signal by comparing the sense signal and the reference signal;
- sampling the comparison signal to generate 2N+1 data values;
- and
- determining the hard bit and the N soft bits based on the 2N+1 data values.
A circuit for reading a hard bit and N soft bits of a memory cell of a nonvolatile memory system in response to a single read command, the circuit comprising:
- a reference generator for generating at a reference output signal node a reference signal that comprises 2N+1 distinct reference signal values;
- a sense amplifier that includes a reference input signal node coupled to the reference output signal node of the reference generator, and a current sense input signal node coupled to receive a current of the memory cell, the sense amplifier configured to:
- generate a sense signal at a sense signal node proportional to the received current;
- and
- generate 2N+1 data values, each data value based on a comparison between the sense signal and a corresponding one of the 2N+1 reference signal values;
- and
- a processor for determining the hard bit and the N soft bits based on the 2N+1 data values.
A method for reading a hard bit and N soft bits of a memory cell of a nonvolatile memory system in response to a single read command, the method comprising:
- providing a reference generator for generating at a reference output signal node a reference signal that comprises 2N+1 distinct reference signal values;
- providing a sense amplifier that includes a reference input signal node coupled to the reference output signal node of the reference generator, and a current sense input signal node coupled to receive a current of the memory cell, the sense amplifier configured to:
- generate a sense signal at a sense signal node proportional to the received current;
- and
- generate 2N+1 data values, each data value based on a comparison between the sense signal and a corresponding one of the 2N+1 reference signal values;
- and
- providing a processor for determining the hard bit and the N soft bits based on the 2N+1 data values.
Dependencies are inferred from the claim text.