Semiconductor memory having a plurality of word lines shared by adjacent local block
View Patent ↗A semiconductor memory device that speeds up its operation. A multiplexer puts one of word lines into an active state to select one memory cell in each local block. Another multiplexer puts one of local block selection signals into an active state and puts one of p-channel transistors into the ON state to select one of local blocks arranged in a column direction. A NAND element inverts the logical product of a signal output from a local block selected by a local block selection signal and a signal output from a block not selected and outputs a result obtained to put an n-channel transistor into the ON or OFF state. The n-channel transistor grounds a common bit line when it goes into the ON state. Each of the p-channel transistors is selected by a column switch (not shown) and send read data to a data bus.
1. A semiconductor static random access memory which includes a memory cell array comprised of a plurality of static memory cells, the semiconductor memory device comprising:
a plurality of local blocks which are arranged in a column direction, said plurality of local blocks being formed by dividing said memory cell array in the column direction and data being read or written by the local blocks;
a divided bit line which is provided for each of the local blocks;
a plurality of word lines which are shared by the local blocks;
a common bit line which is shared by the local blocks;
a first selection circuit which controls the word lines to select one or more of the cells one at a time from each of the local blocks;
a second selection circuit which selects a predetermined local block from the plurality of local blocks; and
a data detection circuit which receives the divided bit line connected to a selected memory cell detects data held in the selected memory cell based on a level of the divided bit line and drives the common bit line to a level corresponding to the detected data, said data detection circuit being provided between the divided bit line and the common bit line, said selected memory cell being selected by said first selection circuit and included in the local block selected by said second selection circuit.
2. A semiconductor static random access memory which includes a cell array comprised of a plurality of static memory cells, the semiconductor memory device comprising:
a plurality of local blocks which are arranged in a column direction, said plurality of local blocks being formed by dividing said memory cell array in the column direction and data being read or written by the local blocks;
a divided bit line which is provided for each of the local blocks;
a plurality of word lines which are shared by the local blocks;
a common bit line which is shared by the local blocks;
a first group of selection lines arranged parallel to the column direction for selecting a predetermined local block from the plurality of local blocks arranged in the column direction;
a second group of selection lines arranged parallel to the column direction for selecting a predetermined memory cell included in each of the local blocks; and
a selection circuit for selecting a predetermined memory cell from the plurality of memory cells included in the column by performing a logical operation on corresponding wirings among the first group of selection lines and the second group of selection lines; and
a data detection circuit which receives the divided bit line connected to the selected memory cell, detects data held in the selected memory cell based on a level of the divided bit line and drives the common bit line to a level corresponding to the detected data, said data detection circuit being provided between the divided bit line and the common bit line.
3. The semiconductor memory device according to claim 2 , further comprising control circuits for controlling a predetermined circuit included in each local block on the basis of a signal applied to the first group of selection lines.
4. The semiconductor memory device according to claim 3 , wherein the predetermined circuit is a pre-charge circuit for pre-charging bit lines which connect memory cells included in each local block to one another.
5. The semiconductor memory device according to claim 3 , wherein the predetermined circuit is a write amplifier, a sense amplifier, a write error protection circuit, or a read error protection circuit.
6. A semiconductor memory device in which includes a memory cell array comprised of a plurality of memory cells, the semiconductor memory device comprising:
a plurality of local blocks which are arranged in a column direction, said plurality of local blocks being formed by dividing said memory cell array in the column direction and data being read or written by the local blocks; and
control circuits located according to the local blocks for controlling the memory cells for data write or read, wherein each of the control circuits shares a well common to an adjacent memory cell.
7. The semiconductor memory device which includes a memory cell array comprised of a plurality of memory cells, the semiconductor memory comprising:
a plurality of local blocks which are arranged in a column direction, said plurality of local blocks being formed by dividing said memory cell array in the column direction and data being, read or written by the local block, wherein:
two adjacent local blocks arranged in the column direction form a pair;
a control circuit is located in a center of two adjacent local blocks being controlled as pair; and
an area where the local block and the control circuit adjoin includes the same well.
8. The semiconductor memory device which includes a memory cell array comprised of a plurality of memory cells, the semiconductor memory comprising:
a plurality of local blocks which are arranged in a column direction, said plurality of local blocks being formed by dividing said memory cell array in the column direction and data being, read or written by the local block, wherein:
two adjacent local blocks arranged in the column direction form a pair;
a control circuit is located in a center of two local blocks adjacent local blocks to control the pair;
other control circuits are located in an area which is opposite to the control circuit in each pair block; and
other control circuits which are adjacent to each other include the same well.
9. A semiconductor memory device which includes a memory cell array comprised of a plurality of memory cells, the semiconductor memory device comprising:
a plurality of local blocks which are arranged in a column direction, said plurality of local blocks being formed by dividing said memory cell array in the column direction and data being read or written by the local blocks;
a write enable signal generation circuit for generating a write enable signal to indicate timing with which data are written into one of said memory cells; and
a memory cell selection signal generation circuit for generating a memory cell selection signal to select said one of said memory cells from which data are to be read or into which data are to be written,
wherein said memory cell selection signal generation circuit accepts said write enable signal, generates said memory cell selection signal with a first timing at a read time on the basis of said write enable signal, and generates said memory cell selection signal with a second timing which is delayed for a predetermined period of time after said first timing at a write time on the basis of said write enable signal.
10. The semiconductor memory device according to claim 9 , wherein:
said memory cell selection signal generation circuit includes:
a selection circuit for accepting an address signal and said write enable signal;
a delay circuit for delaying said address signal outputted from said selection circuit for said predetermined period of time and for outputting said delayed address signal; and
a decode circuit for accepting said address signal outputted from said selection circuit or said delay circuit and for generating said memory cell selection signal on the basis of said address signal inputted; and
said selection circuit provides said address signal to said delay circuit at the time of said write enable signal being active and provides said address signal to said decode circuit at the time of said write enable signal being inactive.