Block switch in flash memory device
View Patent ↗Disclosed herein is a block switch of a flash memory device in which a voltage higher than a predetermined operating voltage is generated to drive path transistors in order to stably apply the predetermined operating voltage to a selected cell block of the flash memory device. The block switch generates a high voltage clock signal of a high voltage level according to a control signal and a clock signal, and raises the voltage level of an output terminal to a predetermined level according to the high voltage clock signal. Accordingly, a high voltage can be outputted even at a low power supply voltage. There is no need for a decoder for high voltage as in a precharge and self-boosting mode. A voltage can be directly applied to word lines without a precharge operation. It is thus possible to reduce an operating time.
1. A block switch of a flash memory device, comprising:
first switching means to transfer a select signal of a power supply voltage level to an output terminal so that the output terminal maintains a first potential;
second switching means to apply a pumping voltage to a node according to the potential of the output terminal so that the node maintains a second potential;
high voltage clock generating means to output a high voltage clock signal higher than the power supply voltage according to the select signal and a clock signal;
a capacitor which is charged according to the high voltage clock signal so that the node maintains a third potential; and
third switching means that supplies the potential of the node to the output terminal according to the potential of the node so that the output terminal maintains a fourth potential,
wherein the capacitor is repeatedly charged with the high voltage according to the clock signal so that the potential of the output terminal rises to a predetermined potential.
2. The block switch as claimed in claim 1 , wherein the high voltage clock generating means comprises:
a NAND gate to invert the clock signal according to the select signal; and
a level shifter to output the high voltage clock signal higher than the power supply voltage according to the output signal of the NAND gate.
3. A block switch of a flash memory device, wherein the flash memory device comprises:
a plurality of cell blocks including a plurality of cell strings to which a plurality of cells is serially connected, wherein one bit line is allocated to each of the cell strings, and a plurality of the cells that share one word line among the plurality of the cells comprises a page;
a plurality of block switches that output a predetermined voltage to select the cell block;
a predecoder that applies operation voltages of a high voltage for a predetermined operation to the cell block through a plurality of global word lines; and
path transistors to apply a predetermined voltage through the global word lines to the word line of the cell block according to an output signal of the block switch,
wherein the block switch is adapted to generate a high voltage clock signal higher than a power supply voltage according to a select signal and a clock signal of the power supply voltage level and raise the level of an output terminal to a predetermined level according to the high voltage clock signal, Wherein the block switch comprises: first switching means for transferring the select signal of the power supply voltage level to the output terminal so that the output terminal maintains a first potential; second switching means for applying a pumping voltage to a node according to the potential of the output terminal so that the node maintains a second potential; high voltage clock generating means for outputting the high voltage clock signal higher than the power supply voltage according to the select signal and the clock signal; a capacitor which is charged according to the high voltage clock signal so that the node maintains a third potential; and third switching means that supplies the potential of the node to the output terminal according to the potential of the node so that the output terminal maintains a fourth potential, wherein the capacitor is repeatedly charged with the high voltage according to the clock signal so that the potential of the output terminal rises to a predetermined potential.
4. The block switch as claimed in claim 3 , wherein the select signal and the clock signal maintain a power supply voltage level.
5. The block switch as claimed in claim 3 , further comprising high voltage clock generating means for outputting the high voltage clock signal higher than the power supply voltage according to the select signal and the clock signal.
6. The block switch as claimed in claim 3 , further comprising a capacitor, which is charged according to the high voltage clock signal, so that the potential of the output terminal is increased.
7. The block switch as claimed in claim 3 , wherein the high voltage clock generating means comprises:
a NAND gate for inverting the clock signal according to the select signal; and
a level shifter for outputting the high voltage clock signal higher than the power supply voltage according to the output signal of the NAND gate.