Sandisk Technologies Inc.

Chia-Kai Chou

Ohwon Kwon

Kou Tei

Tai-Yuan Tseng

Iris Lu

Jongyeon Kim

Mohan Dunga

Hao Nguyen

Hiroki Yabe

Arka Ganguly

Yuedan Li

Sirisha Bhamidipati

Apparatuses and techniques are described for reducing the number of latches used in sense circuits for a memory device. The number of internal user data latches in a sense circuit is reduced by using an external data transfer latch to store a bit of user data, in place of an internal user data latch. The user data in the data transfer latches identifies a subset of the data states which are not prohibited from having a verify test. The subset is shifted as the program operation proceeds, at specified program loops, to encompass higher data states. The completion of programming by a memory cell is indicated by the user data latches and another internal latch of the sense circuit in place of the external data transfer latch.

Window program verify to reduce data latch usage in memory device

A local data bus of a sense amplifier associated with one bit line is used to perform logical operations for a sensing operation performed by another sense amplifier associated with a different bit line. Each sense amplifier circuit includes a sensing node that is pre-charged, then discharged through a selected memory cell and a local data bus with a number of data latches connected. Target program data can be stored in the latches and combined in logical combinations with the sensed value of the memory cell to determine whether it has verified. By including a transfer circuit between the local data buses of a pair of sense amplifiers, the logical operations of a first sense amplifier can be performed using the local data bus of the paired sense amplifier, freeing the first sense amplifier's sense node to be concurrently pre-charged for a subsequent sensing operation, thereby improving performance.

Sense amplifier structure for non-volatile memory with neighbor bit line local data bus data transfer

A storage device is disclosed herein. The storage device, comprises: a non-volatile memory including control circuitry and an array of memory cells formed using a set of word lines and a set of bit lines; and a reference current generator circuit configured to receive an input voltage from a voltage supply and generate therefrom a plurality of outputs, each output of the plurality of outputs used to generate one or more bias voltages/currents for one or more control signals. The control circuitry is configured to: receive a refresh read operation command; and adapt operation of the reference current generator circuit based on receiving the refresh read operation command. This proposal is also applicable for other test modes, such as SA stress, soft and preprogram, and SA test modes.

Reference current generator control scheme for sense amplifier in NAND design

An example of an apparatus includes a plurality of memory cells arranged in a plurality of NAND strings that are connected to a source line and a control circuit connected to the source line. The control circuit is configured to provide a first current to the source line to pre-charge the source line to a target voltage for sensing data states of the plurality of memory cells and provide a second current to the source line to return the source line to the target voltage in a recovery period between sensing data states. The control circuit is configured to provide the second current at any one of a plurality of current levels.

Source line voltage control for NAND memory

An apparatus and method for a multi-state verify of a memory array are provided. A sense circuit of a memory device is connected to a bit line of the memory array. The sense circuit includes a first voltage clamp, a second voltage clamp, and a program data latch disposed on the bit line. The first and second voltage clamps are biased to first and second voltages, respectively, where the first voltage is lower than the second voltage. When a high bias is applied to the program data latch, the program data latch is in an OFF state, and the first voltage clamp limits the bias on the bit line to the first voltage. When a low bias is applied to the program data latch, the program data latch is in an ON state, and the second voltage clamp limits the bias on the bit line to the second voltage.

Multi BLCS for multi-state verify and multi-level QPW

A sense amplifier for a memory circuit that can sense into the deep negative voltage threshold region is described. A selected memory cell is sensed by discharging a source line through the memory cell into the bit line and sense amplifier. While discharging the source line through the memory cell into the sense amplifier, a voltage level on the discharge path is used to set the conductivity of a discharge transistor to a level corresponding to the conductivity of the selected memory cell. A sense node is then discharged through the discharge transistor. By allowing the sense amplifier to bias a memory cell being sensed to a selected one of multiple bias levels during a sensing operation, multiple target data states can be concurrently program verified, leading to higher performance when writing data.

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Newark, CA, United States of America

Chia-Kai Chou