Bit line voltage supply circuit in semiconductor memory device and voltage supplying method therefor
There is provided a bit line voltage supply circuit for reducing leakage current flowing from bit lines to a memory cell without substantially deteriorating the performance of a semiconductor memory device. A bit line voltage switch applies a first supply voltage to a bit line pair in response to a first switch control signal, and applies a second supply voltage having a lower voltage than the first supply voltage to the bit line pair in response to a second switch control signal. A bit line voltage controller controls the first and second switch control signals so that the second supply voltage is supplied to the bit line pair during a standby mode, and the first supply voltage is supplied to the bit line pair when the semiconductor memory device changes from the standby mode to an operational mode for a predetermined time period.
1. A bit line voltage supply circuit in a semiconductor memory device, comprising:
a bit line voltage switch for applying a first supply voltage to a bit line pair in response to a first switch control signal, and for applying a second supply voltage having a lower voltage than the first supply voltage to the bit line pair in response to a second switch control signal; and
a bit line voltage controller for controlling the first and second switch control signals so that the second supply voltage is supplied to the bit line pair in a standby mode, and the first supply voltage is supplied to the bit line pair for a predetermined time period when the semiconductor memory device changes from the standby mode to an operational mode;
wherein the bit line voltage controller includes:
a Y-main decoder for generating the first switch control signal as an equalization and precharge control signal using a block select signal, a bit line select signal, and a chip select association signal; and
a bit line level controller for generating the chip select association signal and the second switch control signal in response to the block select signal and a chip select signal.
2. The bit line voltage supply circuit according to claim 1 , wherein the bit line voltage switch includes:
first and second precharge transistors having source terminals that are connected to the first supply voltage, having drain terminals that are each connected to one of the bit lines of the bit line pair, and having gates for receiving the first switch control signal; and
first and second drive transistors having source terminals that are connected to the second supply voltage, having drain terminals that are each connected to one of the bit lines of the bit line pair, and having gates for receiving the second switch control signal.
3. The bit line voltage supply circuit according to claim 2 , further comprising an equalization transistor including a gate for receiving the first switch control signal, and a source-drain channel of the equalization transistor that is connected between the drains of the first and second precharge transistors.
4. The bit line voltage supply circuit according to claim 2 , wherein the semiconductor memory device is a static random access memory, and the static random access memory includes a plurality of memory cells, each memory cell having six cell transistors.
5. The bit line voltage supply circuit according to claim 4 , wherein the six cell transistors are a three-dimensional memory cell that is formed on different conductive layers.
6. A method of supplying a bit line voltage in a semiconductor memory device, comprising:
generating the first switch control signal as an equalization and precharge control signal using a block select signal, a bit line select signal, and a chip select association signal;
generating the chip select association signal and the second switch control signal in response to the block select signal and a chip select signal;
in response to the first switch control signal, applying a standby voltage that is lower than an operating voltage to a bit line pair during a standby mode; and
in response to the second switch control signal, applying the operating voltage to the bit line pair when the semiconductor memory device changes from the standby mode to an operational mode.
7. A method of supplying a bit line voltage in a semiconductor memory device, comprising:
applying a standby voltage that is lower than an operating voltage to a bit line pair during a standby mode; and
applying the operating voltage to the bit line pair when the semiconductor memory device changes from the standby mode to an operational mode;
wherein the operating voltage is identical to a level of a bit line precharge voltage, and the standby voltage level is generated by a write driver connected to a column pass gate.
8. A method of supplying a bit line voltage in a semiconductor memory device, comprising:
applying a voltage lower than an operating voltage to a bit line pair of the semiconductor memory device in a standby mode to reduce a standby current;
applying a voltage higher than the operating voltage to the bit line pair for a predetermined time period when the semiconductor memory device changes from the standby mode to an operational mode; and
applying the operating voltage as the bit line voltage when the predetermined time period elapses.