Semiconductor integrated circuit device
View Patent ↗There is achieved a high-integrated and high-speed nonvolatile memory which can stabilize an operation of a phase-change memory for a short operation cycle time. A latch is provided in a write driver. A change to a high-resistance state of a phase-change element is performed per column cycle by a write-enable signal, and a change to a low-resistance state thereof is performed after a pre-charge command is inputted and concurrently with deactivation of a pre-charge signal. Thereby, a write time to a memory cell in which phase-change resistance is changed to a low-resistance state, and a period from a write operation for changing the phase-change resistance to a high-resistance state to a read operation to the above memory cell can be lengthened without extending the column cycle time, so that the stable write operation is achieved.
1. A semiconductor integrated circuit device comprising:
a plurality of word lines;
a plurality of bit lines crossing the plurality of word lines;
a plurality of memory cells disposed at predetermined crossings between the plurality of word lines and the plurality of bit lines;
a plurality of sense amplifiers connected to the plurality of bit lines; and
a plurality of write drivers connected to the plurality of sense amplifiers and each including a first write switch writing first information to corresponding memory cells and a second write switch writing second information to the corresponding memory cells,
wherein the first write switches of write drivers which are connected to sense amplifiers holding the first information are activated after four data are inputted to a data input buffer, and
wherein the second write switches of write drivers which are connected to sense amplifiers holding the second information are activated after activating the first write switches to write the first information before starting a pre-charge operation.
2. The semiconductor integrated circuit device according to claim 1 ,
wherein the first switches are activated in response to activation of a write enable signal,
wherein the second switches are activated in response to inactivation of an active standby pre-charge signal,
wherein the write enable signal is activated in response to input of a write command, and
wherein the active standby pre-charge signal is inactivated in response to input of a pre-charge command.
3. The semiconductor integrated circuit device according to claim 1 ,
wherein each said sense amplifier includes:
a first data retaining circuit holding data for the corresponding memory cells or write data from outside; and
a second data retaining circuit holding a write selection history.
4. The semiconductor integrated device according to claim 1 ,
wherein a period during which the first write switches are activated is shorter than a period during which the second write switches are activated.
5. The semiconductor integrated device according to claim 1 ,
wherein the plurality of memory cells are non-volatile memory cells.
6. The semiconductor integrated device according to claim 1 ,
wherein each memory cell includes a phase-change resistance which changes a resistance value by application of a current.