Page buffer for nonvolatile semiconductor memory device and method of operation

1. A page buffer for a nonvolatile semiconductor memory device, the page buffer comprising:

a loading latch unit adapted to load and store a data bit in a latch node;

a unidirectional driver adapted to receive the data bit from the loading latch unit and drive a corresponding write data bit onto a bitline connected to a memory cell, wherein the unidirectional driver is connected between the loading latch unit and the bitline such that during a program operation of the memory cell, the data bit stored in the latch node is prevented from being flipped in response to a voltage level apparent on the bitline; and

a sensing detector adapted to flip a logic state of the data bit stored in the latch node according to a voltage level apparent on the bitline, the sensing detector being enabled in response to a read latch signal.

2. The page buffer of claim 1 , wherein the unidirectional driver comprises an inverter.

3. The page buffer of claim 2 , further comprising:

an output driver adapted to receive a data bit output by the unidirectional driver and provide a corresponding data bit to a data output line.

4. The page buffer of claim 1 , further comprising:

a buffer selection unit adapted to receive a data bit from the unidirectional driver and selectively provide the data bit to the bitline in response to a buffer selection signal.

5. A page buffer for a nonvolatile semiconductor memory device, the page buffer comprising:

a loading latch unit adapted to load and store a data bit in a latch node;

a unidirectional driver adapted to receive the data bit from the latch node and driving a corresponding write data bit onto a bitline by way of a sensing node, wherein the bitline is connected to a memory cell, wherein the unidirectional driver is connected between the loading latch unit and the bitline such that during a program operation of the memory cell, the data bit stored in the latch node is prevented from being flipped in response to a voltage level apparent on the bitline;

a sensing detector adapted to flip a logic state of the data bit stored at the latch node according to a voltage level apparent at the sensing node, the sensing detector being enabled in response to a read latch signal; and,

a buffer selection unit receiving the write data bit from the unidirectional driver and sending the write data bit to the bitline by way of the sensing node in response to a buffer selection signal.

6. The page buffer of claim 5 , wherein the unidirectional driver comprises an inverter receiving the data bit stored in the latch node and sending an output to the buffer selection unit.

7. The page buffer of claim 6 , further comprising:

an output driver receiving the output from the unidirectional driver and sending a corresponding data bit to a data output line.

8. A method of operating a page buffer for a nonvolatile semiconductor memory device, the method comprising:

loading a data bit to a latch node in a loading latch unit;

receiving the data bit from the loading latch unit and outputting a corresponding write data bit to a bitline using a unidirectional driver, wherein the bitline is connected to a memory cell and the unidirectional driver is connected between the loading latch unit and the bitline such that during a program operation of the memory cell, the data bit loaded to the latch node is prevented from being flipped in response to a voltage level apparent on the bitline;

flipping the data bit loaded to the latch node according to a voltage level of the bitline while a read latch signal is activated.

9. The method of claim 8 , wherein the unidirectional driver comprises an inverter.

10. The method of claim 8 , further comprising:

receiving the write data bit from the unidirectional driver and sending the write data bit to the bitline by way of a sensing node in response to a buffer selection signal.

11. The method of claim 8 , further comprising:

sending an output from the unidirectional driver to a data output line.