Memory device and bit line precharging method during program verify operation in the memory device
A memory device includes bit lines coupled to a memory block, a page buffer group selecting the bit lines in response to page buffer signals, applying a precharge voltage to selected bit lines from among the bit lines, and applying a ground voltage to unselected bit lines during a program verify operation, and a page buffer controller outputting the page buffer signals to selectively apply the precharge voltage to the bit lines according to an order of read operations on a logical page during the program verify operation.
1. A memory device, comprising:
bit lines coupled to memory cells storing data which is composed of a plurality of logical pages;
a voltage generator generating read voltages during read operations according to an order of the read operations, or generating verify voltages corresponding to the read voltages during a program verify operation;
a page buffer controller determining bit lines to apply a precharge voltage or a ground voltage according to the verify voltages and the read voltages for a selected logical page among the plurality of logical pages, and outputting page buffer signals according to determination of the bit lines; and
a page buffer group applying the precharge voltage or the ground voltage to the bit lines in response to the page buffer signals when the program verify operation is performed,
wherein the page buffer group is configured to:
when a first verify operation using a first verify voltage corresponding to a first read voltage of the selected logical page is performed, apply the precharge voltage to the bit lines coupled to all of the memory cells, wherein the first read voltage is a lowest read voltage among the read voltages used for the selected logical page; and
when a second verify operation using a second verify voltage corresponding to a second read voltage of the selected logical page is performed, apply the ground voltage to bit lines coupled to memory cells corresponding to a threshold voltage lower than the first read voltage, and apply the precharge voltage to remaining bit lines.
2. The memory device of claim 1 , wherein the plurality of logical pages include logical data composed of first logical data, second logical data and third logical data.
3. The memory device of claim 2 , wherein the selected logical page is one of the first logical data, the second logical data and the third logical data.
4. A method of operating a memory device, the method comprising:
determining bit lines to apply a precharge voltage or a ground voltage according to verify voltages and read voltages for a selected logical page among a plurality of logical pages;
applying the precharge voltage to the bit lines coupled to all of memory cells, when a first verify operation using a first verify voltage corresponding to a first read voltage of the selected logical page is performed; and
applying the ground voltage to bit lines coupled to memory cells corresponding to a threshold voltage lower than the first read voltage, and applying the precharge voltage to remaining bit lines, when a second verify operation using a second verify voltage corresponding to a second read voltage of the selected logical page is performed.
5. The method of claim 4 , wherein the plurality of logical pages include logical data composed of first logical data, second logical data and third logical data.
6. The method of claim 5 , wherein the selected logical page is one of the first logical data, the second logical data and the third logical data.