Semiconductor memory device

The present invention relates to a semiconductor memory device, and more particularly, to a precharge circuit for local input/output lines in a semiconductor memory device.

Typically, a semiconductor memory device that has a stack bank structure includes a plurality of banks, each configured with a group of memory cell arrays, each of which includes memory cells. The banks are arranged in the direction of word lines, and the memory cell arrays are also arranged in the direction of word lines and connected to local input/output lines. The local input/output lines serve as data transmission lines by being connected to global input/output lines. The local input/output lines are prepared as many as the divided banks and connected with precharge circuits to precharge the individual local input/output lines.

FIG. 1 illustrates a block diagram depicting a portion of one bank, which is divided into several regions depending on an output mode of data of a semiconductor memory device. For instance, for double data rate (DDR) memory devices, one bank is divided into 4 regions (often called “quarter bank”) since DDR memory devices performs a 4-bit pre-patch operation. In the case of a 16-bit data output mode, 16 bits of data are outputted from one quarter bank.

In particular, FIG. 1 illustrates a block diagram of conventional local input/output line precharge units and a precharge control signal generator for the local input/output line precharge units in one quarter bank, which is divided into a plurality of cell blocks.

The local input/output line precharge units LIOPCG 1 to LIOPCG 8 are controlled by the precharge control signal generator 103 . The local input/output line precharge units LIOPCG 1 to LIOPCG 8 are disposed on one side of upper and lower local input/output lines 101 and 102 connected with the cell blocks, each including a predetermined number of unit cells to satisfy a data output operation mode of the semiconductor memory device. The cell blocks are also divided into a group of upper cell blocks Up Half and a group of lower cell blocks Down Half.

The upper and lower cell blocks Up Half and Down Half are connected respectively to the upper and lower local input/output lines 101 and 102 , which are data transmission lines. In one quarter bank, there are write drivers WTDRV 1 to WTDRV 8 and the local input/output line precharge units LIOPCG 1 to LIOPCG 8 . The write drivers WTDRV 1 to WTDRV 8 transfer data to the upper and lower local input/output lines 101 and 102 from global input/output lines. The local input/output line precharge units LIOPCG 1 to LIOPCG 8 precharge the upper and lower local input/output lines 101 and 102 .

The upper and lower cell blocks UP Half and Down Half are arranged symmetrically. The upper cell blocks UP Half are connected with the upper local input/output lines 101 , and the lower cell blocks Down Half are connected with the lower local input/output lines 102 . The write drivers WTDRV 1 to WTDRV 8 and the local input/output line precharge units LIOPCG 1 to LIOPCG 8 are individually connected with the respective upper and lower local input/output lines 101 and 102 .

The cell blocks are grouped into a group of the upper cell blocks Up Half and a group of the lower cell blocks Down Half to effectively use the banks due to the data processing condition of the semiconductor memory device, and thus to reduce the current dissipation. The local input/output line precharge units LIOPCG 1 to LIOPCG 8 perform a precharge operation in response to a local input/output line reset signal LIORST.

For instance, in the case of a 4-bit or 8-bit data output operation mode, data are outputted through the upper local input/output lines 101 or the lower local input/output lines 102 that are connected with the 8 cell blocks. In the case of a 16-bit data output operation mode, data are outputted through the local input/output lines 101 and 102 connected with the 16 cell blocks. The reason for this behavior is that only the 8 cell blocks are used for the 4-bit and 8-bit data output modes and the 16 cell blocks are used for the 16-bit data output mode.

However, the local input/output line precharge units LIOPCG 1 to LIOPCG 8 usually do not have a control signal for the 4-bit or 8-bit data output operation mode. Thus, the local input/output line precharge units LIOPCG 1 to LIOPCG 8 precharge the upper local input/output lines 101 and the lower input/output lines 102 at the same time. That is, the upper and lower local input/output lines 101 and 102 connected with the 16 cell blocks are all precharged. As a result, when the 4-bit or 8-bit data output operation mode is performed, the upper and lower local input/output lines 101 and 102 connected with the 16 cell blocks are all precharged unnecessarily, thereby resulting in current dissipation.

In more detail, the local input/output line reset signal LIORST is used to control the local input/output line precharge units LIOPCG 1 to LIOPCG 8 . However, when the local input/output line reset signal LIORST is supplied to the individual local input/output line precharge units LIOPCG 1 to LIOPCG 8 , the local input/output line reset signal LIORST is not usually controlled by the 4-bit, 8-bit and 16-bit data output operation mode but simply by three inverters INV 1 , INV 2 and INV 3 of the precharge control signal generator 103 . Accordingly, it is necessary to develop a device that can precharge separately the cell blocks according to the operation mode so as to reduce the current dissipation.

It is, therefore, an object of the present invention to provide a semiconductor memory device that can reduce unnecessary dissipation of current by selectively precharging local input/output lines coupled to corresponding block banks.

In accordance with an aspect of the present invention, there is provided a semiconductor memory device, including: a bank including a plurality of cell blocks; a first group of local input/output lines to transfer data stored on a first group of the cell blocks according to a first data output mode; a second group of local input/output lines to transfer data stored on a second group of the cell blocks according to the first data output mode and a second data output mode; a first precharge unit precharging the first group of the local input/output lines; a second precharge unit precharging the second group of the local input/output lines; a precharge signal generator to precharge the first and second groups of the cell blocks for the first data output mode and the second group of the cell blocks for the second data output mode.

In accordance with another aspect of the present invention, there is provided a semiconductor memory device, including: an upper memory block to output stored data according to a first data output mode; a lower memory block to output stored data according to the first data output mode and a second data output mode; a first precharge unit to precharge local input/output lines of the upper memory block; a second precharge unit to precharge local input/output lines of the lower memory block; and a precharge controller controlling the first and second precharge units according to the first data output mode or the second data output mode.

The above and other objects and features of the present invention will become better understood with respect to the following description of the exemplary embodiments given in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates a block diagram of conventional local input/output line precharge units and a precharge control signal generator for the conventional local input/output line precharge units; and

FIG. 2 illustrates a block diagram of local input/output line precharge units and a precharge control signal generator for the local input/output line precharge units in accordance with an embodiment of the present invention.

A semiconductor memory device in accordance with various embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 illustrates a block diagram of local input/output line precharge units and a precharge control signal generator for the local input/output line precharge units in accordance with an embodiment of the present invention.

The local input/output line precharge units LIOPCG 11 to LIOPCG 18 are prepared on one side of upper and lower local input/output lines 205 and 207 coupled to cell blocks each including a predetermined number of unit cells to satisfy an intended data output operation mode of the semiconductor memory device. Also, the cell blocks are divided into a group of upper cell blocks UP Half and a group of lower cell blocks Down Half.

The upper and lower cell blocks Up Half and Down Half are arranged symmetrically. The upper cell blocks Up Half are coupled to the upper local input/output lines 205 , while the lower cell blocks Down Half are coupled to the lower local input/output lines 207 . Write driving units WTDRV 11 to WTDRV 18 and the local input/output line precharge units LIOPCG 11 to LIOPCG 18 are individually coupled to the respective upper and lower local input/output lines 205 and 206 . The local input/output line precharge units LIOPCG 11 to LIOPCG 18 are grouped into an upper precharge unit group including those local input/output line precharge units LIOPCG 11 , LOPPCG 13 , LIOPCG 15 , and LIOPCG 17 , which are coupled to the upper local input/output lines 205 , and a lower precharge unit group including those local input/output line precharge units LIOPCG 12 , LIOPCG 14 , LIOPCG 16 and LIOPCG 18 , which are coupled to the lower local input/output lines 206 . The precharge control signal generator 209 precharges the upper precharge unit group and the lower precharge unit group.

The precharge control signal generator 209 for the local input/output precharge units LIOPCG 11 to LIOPCG 18 includes a precharge selection signal generation unit 201 and a precharge signal generation unit 203 . The precharge selection signal generation unit 201 generates first and second precharge selection signals C 0 and C 1 selecting the upper precharge unit group and the lower precharge unit group. The precharge signal generation unit 203 generates precharge signals in response to the first and second precharge selection signals C 0 and C 1 and a local input/output line reset signal LIORST, and transmits the precharge signals selectively to the upper precharge unit group and the lower precharge unit group through corresponding lines 211 and 213 .

The precharge selection signal generation unit 201 includes an NOR gate NOR 1 , an inverter INV 4 , a first NAND gate NAND 1 , and a second NAND gate NAND 2 . The NOR gate NOR 1 receives a signal x 4 instructing a 4-bit data output operation mode and a signal x 8 instructing an 8-bit data output operation mode. The inverter INV 4 inverts an output signal of the NOR gate NOR 1 . The first NAND gate NAND 1 receives an output signal of the inverter INV 4 and an internal address signal AX< 13 > and outputs the first precharge selection signal C O . The second NAND gate NAND 2 receives the first precharge selection signal C O and the output signal of the inverter INV 4 and outputs the second precharge selection signal C 1 .

The precharge signal generation unit 203 may include a first group of inverters INV 5 and INV 6 , a second group of inverters INV 7 and INV 8 , a third group of inverters INV 9 and INV 10 , a first NAND gate NAND 3 , and a second NAND gate NAND 4 . The first group of the inverters INV 5 and INV 6 inverts the local input/output line reset signal LIORST that resets the local input/output lines 205 and 207 . The second group of the inverters INV 7 and INV 8 inverts the first precharge selection signal C O . The third group of the inverters INV 9 and INV 10 inverts the second precharge selection signal C 1 . The first NAND gate NAND 3 receives output signals of the first and second groups of the inverters INV 5 to INV 8 and outputs a first precharge signal to the upper precharge group LIOPCG 11 , LIOPCG 13 , LIOPCG 15 , and LIOPCG 17 . The second NAND gate NAND 4 receives output signals of the first and third groups of the inverters INV 5 , INV 6 , INV 9 and INV 10 and outputs a second precharge signal to the lower precharge group LIOPCG 12 , LIOPCG 14 , LIOPCG 16 , and LIOPCG 18 .

Table provided below briefly shows operations of the semiconductor memory device according to an embodiment of the present invention.

In the 16-bit data output operation mode, the upper local input/output lines 205 and the lower local input/output lines 207 are precharged. In the 4-bit or 8-bit data output operation mode, the first and second precharge selection signals C 0 and C 1 are combined to selectively precharge the upper local input/output lines 205 and the lower local input/output lines 207 .

According to exemplary embodiments of the present invention, precharge signals are generated to selectively precharge local input/output lines coupled to the corresponding cell blocks. Therefore, the selective precharge of the local input/output lines can reduce unnecessary current dissipation.

The present application contains subject matter related to the Korean patent application Nos. KR 2005-0090841 and 2006-0037512, filed in the Korean Patent Office respectively on Sep. 28, 2005, and on Apr. 26, 2006, the entire contents of which being incorporated herein by reference.

While the present invention has been described with respect to certain preferred embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims.

For instance, the logic types and device layout described in the above embodiments are exemplary implementations when the input signals and output signals are activated to a logic high state. Thus, when the logic states of the signals are changed, the illustrated implementations are also changed. Thus, many other implementations are possible; however, these implementations will not be described in detail to prevent any potential abusive technical adaptation or modification by those skilled in the art.

Also, the precharge signal generation unit 203 and the precharge selection signal generation unit 201 are implemented in multiple logic circuits. However, it should be noted that this exemplary implementation is merely illustrative.