Semiconductor storage device and method for reading stored data

Abstract

The present invention provides a semiconductor memory device capable of improving read characteristics of a sense amplifier and a method of reading stored data. A semiconductor memory device includes a sense amplifier and a controller. The sense amplifier has: a first transistor for clamping the voltage of the bit line; a second transistor provided between the voltage node clamped by the first transistor and a reference voltage node; One transistor clamps the voltage node between the third transistor. The controller, in the first working mode, turns on the first transistor and the second transistor, and turns off the third transistor. In the second operation mode, the third transistor is turned on, and in the third operation mode, the first transistor is turned on, the second transistor is turned off, the third transistor is turned on, and the fourth transistor is turned on.

Description

technical field [0001] Embodiments of the present invention relate to a semiconductor memory device and a method of reading stored data. Background technique [0002] As a large-capacity recording medium, a nonvolatile semiconductor storage device typified by a NAND-type flash memory is used in various electronic devices. Such a nonvolatile semiconductor memory device converts data read from selected memory cells into a desired voltage level via a sense amplifier (sense amplifier). The read operation of the sense amplifier is called sensing (sense, readout). [0003] As one of the sensing methods, an ABL (All Bit Line) method is known. In the ABL method, after precharging the bit lines, a read operation is performed on all the bit lines. Then, based on the amount of current flowing from the bit line, read data from the memory cell is detected. [0004] In the ABL method, the bit line is precharged first. Then, the transistor connected to the sensing node is turned on, a...

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Problems solved by technology

Therefore, it becomes the main cause of the deterioration of the read characteristic of the sense amplifier

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