A method for operating a memory (28) that includes a plurality of analog memory cells (32) includes storing data in the memory by writing first storage values to the cells. Second storage values are read from the cells, and a Cumulative Distribution Function (CDF) of the second storage values is estimated. The estimated CDF is processed so as to compute one or more thresholds. A memory access operation is performed on the cells using the one or more thresholds.

Adaptive Estimation of Memory Cell Read Thresholds

A method for operating a memory (28) includes storing data, which is encoded with an Error Correction Code (ECC), in analog memory cells (32) of the memory by writing respective analog input values selected from a set of nominal values to the analog memory cells. The stored data is read by performing multiple read operations that compare analog output values of the analog memory cells to different, respective read thresholds so as to produce multiple comparison results for each of the analog memory cells. At least two of the read thresholds are positioned between a pair of the nominal values that are adjacent to one another in the set of the nominal values. Soft metrics are computed responsively to the multiple comparison results. The ECC is decoded using the soft metrics, so as to extract the data stored in the analog memory cells.

Reading memory cells using multiple thresholds

A method for operating a memory (28) includes storing data in a group of analog memory cells (32) of the memory as respective first voltage levels. After storing the data, second voltage levels are read from the respective analog memory cells. The second voltage levels are affected by cross-coupling interference causing the second voltage levels to differ from the respective first voltage levels. Cross-coupling coefficients, which quantify the cross-coupling interference among the analog memory cells, are estimated by processing the second voltage levels. The data stored in the group of analog memory cells is reconstructed from the read second voltage levels using the estimated cross-coupling coefficients.

Distortion estimation and cancellation in memory devices

A method for storing data in a memory (28) that includes analog memory cells (32) includes identifying one or more defective memory cells in a group of the analog memory cells. An Error Correction Code (ECC) is selected responsively to a characteristic of the identified defective memory cells. The data is encoded using the selected ECC and the encoded data is stored in the group of the analog memory cells. In an alternative method, an identification of one or more defective memory cells among the analog memory cells is generated. Analog values are read from the analog memory cells in which the encoded data were stored, including at least one of the defective memory cells. The analog values are processed using an ECC decoding process responsively to the identification of the at least one of the defective memory cells, so as to reconstruct the data.

Automatic defect management in memory devices

A method for operating a memory device (24) includes encoding data using an Error Correction Code (ECC) and storing the encoded data as first analog values in respective analog memory cells (32) of the memory device. After storing the encoded data, second analog values are read from the respective memory cells of the memory device in which the encoded data were stored. At least some of the second analog values differ from the respective first analog values. A distortion that is present in the second analog values is estimated. Error correction metrics are computed with respect to the second analog values responsively to the estimated distortion. The second analog values are processed using the error correction metrics in an ECC decoding process, so as to reconstruct the data.

Combined distortion estimation and error correction coding for memory devices

An integrated circuit detects the voltage level of the supply voltage to the integrated circuit. Circuity on the integrated circuit including the charge pump circuity adjusts to operate more effectively or efficiently at the voltage level of the supply voltage.

Charge pump circuit adjustable in response to an external voltage source

Techniques are used to store information in a medium such as the memory cells of an integrated circuit, and also retrieval of information from the medium. The integrated circuit includes nonvolatile memory cells ( 416 ) capable of multilevel or analog voltage level storage. The integrated circuit may store or record information in analog or digital form, or both. Information is stored in and retrieved from the integrated circuit using a user-selected sampling frequency. The user's selection of the sampling frequency is stored within the integrated circuit.

Integrated circuit with analog or multilevel storage cells and user-selectable sampling frequency

Level shifter circuits are used to configure analog or multilevel memory cells. A level shifter circuit generates an output voltage that is above the input voltage by an offset voltage value. The magnitude of this offset voltage or the relationship between the input and output voltages of the level shifter is adjustable or programmably selectable. Adjustments can be made after the integrated circuits is fabricated and packaged. Adjustments are made by configuring bits of data in the integrated circuit to indicate the offset voltage or other parameters. These configuration bits are implemented using latches, flip-flops, registers, memory cells, or other storage circuits.

Adjustable level shifter circuits for analog or multilevel memories

An integrated circuit stores analog or digital information, or both, in memory cells (416). The memory cells provide analog or multilevel storage. Analog information is provided through an analog signal input (405), and digital information is provided through a digital signal input (407). A scheme for storing digital information is consistent with the scheme used to store analog information. Data is retrieved from the memory cells, and output to the analog or digital signal output (454, 463) depending on the type of data. A digital reference generator reference generator (425) generates various analog equivalent voltages for the digital signal input.

Techniques for storing digital data in an analog or multilevel memory

Information is provided in analog (402) or digital (DI) form and is stored in the memory cells (412) of an integrated circuit (400). The memory cells of the integrated circuit are nonvolatile memory cells capable of analog or multilevel storage. The integrated circuit samples (230) the analog information and stores the samples in the memory cells (250) in an analog form. Typically, one cell holds one sample of the analog information. The sampling rate (625) is user-selectable, and an indication of the user's selection of the sampling stored within (661) the integrated circuit. Circuitry on the integrated circuit including charge pumps (3610, 3615, 3620) are adjusted (3423) to operate more effectively or efficiently depending on the supply voltage level (Vext). Level shifter circuitry (1810, 1815, 2430) on the integrated circuit is programmably adjustable. An internal signal path of the integrated circuit can be fully differential.

Leon Sea Jiunn Wong

Papers

Charge pump circuit adjustable in response to an external voltage source

Integrated circuit with analog or multilevel storage cells and user-selectable sampling frequency

Adjustable level shifter circuits for analog or multilevel memories

Techniques for storing digital data in an analog or multilevel memory

Techniques for analog and multilevel storage using integrated circuit technology