Read reference levels are used to distinguish different data states for information stored in non-volatile memory. A storage system recalibrates its read reference levels, to maintain accuracy of the read process, by sensing samples of data for different test read reference levels and using those samples to determine an improved set of read reference levels. At least a subset of the test read reference levels used for the samples are dynamically and adaptively chosen based on indications of error for previous samples.

A system including a processor and a memory device. The memory device includes a memory array having a plurality of memory elements connected to a bit-line and a quantizing circuit. The quantizing circuit includes a combination circuit configured to combine an analog input signal with an analog feedback signal to produce a delta signal. The quantizing circuit also includes an integrator configured to receive and integrate the delta signal to produce a sigma signal. The quantizing circuit also includes an analog-to-digital converter configured to receive the sigma signal and compare the sigma signal with a reference signal to produce a digital output signal.

A non-volatile memory receives a request from a controller to read data stored in the memory. Moving read references are adjusted as a function of the temperature of the memory at which the data was written and the temperature of the memory at which the data is to be read. Moving read references may also be adjusted as a function of the retention time of the data to be read and the word line type of the storage elements in which the data is stored.

A semiconductor device storing data as a multilevel potential is provided. The semiconductor device includes a memory cell, first and second reference cells, first and second sense amplifiers, and first to third circuits. The first circuit has a function of outputting, to a first wiring and a third wiring, a first potential corresponding to a first signal output from the memory cell. The second circuit has a function of outputting, to a second wiring, a first reference potential corresponding to a second signal output from the first reference cell. The third circuit has a function of outputting, to the fourth wiring, a second reference potential corresponding to a third signal output from the second reference cell when a second switch is in an off state. The first sense amplifier refers to the first potential and the first reference potential and changes potentials of the first wiring and the second wiring. The second sense amplifier refers to the first potential and the second reference potential and changes potentials of the third wiring and the fourth wiring.

An method of operating a nonvolatile memory device including a plurality of memory cells comprises receiving a read command from an external device, in response to the read command, performing, based on a reference voltage, a first cell counting operation with respect to the plurality of memory cells, adjusting at least one read voltage of first through nth read voltages (where n is a natural number greater than 1) based on a first result of the first cell counting operation, and performing, based on the adjusted at least one read voltage, a read operation corresponding to the read command with respect to the plurality of memory cells.

A memory device that, in certain embodiments, includes a memory element coupled to a bit-line and a quantizing circuit coupled to the memory element via the bit-line. In some embodiments, the quantizing circuit includes an analog-to-digital converter having an input and output and a digital filter that includes memory. The input of the analog-to-digital converter may be coupled to the bit-line, and the output of the analog-to-digital converter may be coupled to the digital filter.

Methods, systems, and devices for operating a ferroelectric memory cell or cells are described. A memory array may be operated in a half density mode, in which a subset of the memory cells is designated as reference memory cells. Each reference memory cell may be paired to an active memory cell and may act as a reference signal when sensing the active memory cell. Each pair of active and reference memory cells may be connected to a single access line. Sense components (e.g., sense amplifiers) associated with reference memory cells may be deactivated in half density mode. The entire memory array may be operated in half density mode, or a portion of the array may operate in half density mode and the remainder of the array may operate in full density mode.

Methods and apparatus are provided for adaptive read threshold voltage tracking with separate characterization on each side of a voltage distribution about a distribution mean. A read threshold voltage for a memory is adjusted by determining statistical characteristics of two adjacent memory levels based at least in part on a type of statistical distribution of the memory levels and a distribution of data values read from cells using a plurality of read threshold voltages, wherein the statistical characteristics of the two adjacent memory levels are characterized independently on two sides about at least one mean of the statistical distribution; computing an adjusted read threshold voltage associated with the two adjacent memory levels by using the statistical characteristics of the two adjacent memory levels; and updating the read threshold voltage based on the adjusted read threshold voltage. The adjustment is optionally performed responsive to one or more read errors.

Methods, systems, and devices related to auto-referenced memory cell read techniques are described. The auto-referenced read may encode user data to include a certain number bits having a first logic state prior to storing the user data in memory cells. Subsequently, reading the encoded user data may be carried out by applying a read voltage to the memory cells while monitoring a series of switching events by activating a subset of the memory cells having the first logic state. The auto-referenced read may identify a particular switching event that correlates to a median threshold voltage value of the subset of the memory cells. Then, the auto-referenced read may determine a reference voltage that takes into account a statistical property of threshold voltage distribution of the subset of the memory cells. The auto-referenced read may identify a time duration to maintain the read voltage based on determining the reference voltage. When the time duration expires, the auto-referenced read may determine that the memory cells that have been activated correspond to the first logic state.

A non-volatile memory system comprises a memory structure and a control circuit connected to the memory structure. The control circuit includes a programmable and reprogrammable microcontroller. The microcontroller has a first processor that executes instructions to coordinate sequences of voltages applied to the memory structure by a first circuit in order to perform memory operations. The microcontroller has a second processor that executes second instructions to control a second circuit to test conditions of the non-volatile memory cells in response to the voltages applied to the memory structure. The microcontroller may have a third processor that controls the flow of the memory operation and directs the first and second processors to execute the instructions. The instructions of the various processors may be updated, which provides for flexible flow, core operation control, and condition testing.