Methods are disclosed for a dynamic random access memory (DRAM) which ensure that the last write operation in a DRAM column cycle is not turned off before the bit line restore is completed, thus avoiding that data is destroyed in the next access. In addition these methods allow the precharge command to occur before the write data are fully restored. This is achieved by a providing a TWR Protect Circuit which adds a Timing Reference and Timing Compare circuit to the DRAM control logic, such that a last write cycle out of `n` cycles is recognized and that the bit line restore period of the that last write cycle is extended to ensure that bit line BL and BLB reach full voltage.

A dynamic random access memory including a cell array for storing data therein, a column address strobe bar buffer for generating at least one internal column address strobe signal in response to one external column address strobe bar signal to select data from the cell array, and an internal column address strobe enable signal generation circuit for generating at least one internal column address strobe enable signal to control the number of internal column address strobe signals from the column address strobe bar buffer. According to the present invention, one external column address strobe bar pin is used to generate internal multiple column address strobe signals. Therefore, the package size can be reduced and the time skew can be avoided. Furthermore, the internal multiple column address strobe signals are selectively enabled.

A semiconductor memory device includes a memory cell array, an address part for supplying address signals to the memory cell array, a read/write part for reading data from the memory cell array and writing data into the memory cell array, and an internal clock signal generating circuit for generating an internal clock signal from an external clock signal. The internal clock signal has a cycle with an active-level portion of constant duration independent of a frequency of the external clock signal and is output, as a timing signal, to predetermined structural parts of the address part and/or the read/write part.

The present invention relates to a semiconductor memory device, and more particularly to a dynamic random access memory for accomplishing high speed data access by supplying a plurality of row address strobe signals to a chip. A plurality of row address strobe signals are supplied to a plurality of pins, and each row address strobe signal is sequentially supplied with an active signal during a data access operation. Therefore, data in a plurality of memory cell arrays is accessed during one access cycle time. Thus, since a large number of random data are provided, the data access time decreases and the performance of a system can be greatly improved.

In a memory device such as a DRAM or multiport DRAM, each of a plurality of memory cells includes an access transistor with a gate connected to a word line and a storage capacitor with a storage node connected through the access transistor to a digit line. Data is transferred on the digit line to and from the storage capacitor when the word line is activated and the access transistor enabled thereby. According to the present invention, a timing control circuit is provided to control deactivation of the word line. The timing control circuit includes a digit-write/transfer model that simulates a read-write cycle in a DRAM or a serial write transfer operation in a multiport DRAM. The digit-write transfer model produces an output signal indicating the state of the modeled data transfer operation. The timing control circuit also includes a reference voltage circuit and a level comparator. The level comparator compares the model output signal to the reference voltage provided by the reference voltage circuit. The level comparator includes a sensitive analog multi-stage current mirror differential amplifier circuit and produces a signal input to a RAS timing chain circuit which deactivates the word line upon completion of the modeled data transfer operation.