Static information storage and retrieval – Read/write circuit – Flip-flop used for sensing
Reexamination Certificate
2000-04-14
2001-12-04
Elms, Richard (Department: 2824)
Static information storage and retrieval
Read/write circuit
Flip-flop used for sensing
C365S189070, C365S207000
Reexamination Certificate
active
06327203
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to semiconductor devices, and more particularly, to a memory device having minimized power consumption upon reading or writing, and a data reading, and writing method for accomplishing reduced power reading and writing of data.
2. Description of the Related Art
Semiconductor devices such as a dynamic random access memory (DRAM) generally repeat reading and writing of data. However, reading and writing of data consumes a considerable amount of power.
For example, upon reading of data, a bit line sense amplifier senses and amplifies data transferred to a pair of bit lines and transmits the resultant data to a pair of input and output lines. An input and output sense amplifier senses and amplifies data transferred to the pair of input and output lines. The bit line sense amplifier the input and output sense amplifier each consume a certain amount of power during their operation.
Also, upon writing of data, a writing driver transmits write data received from a data input buffer to a pair of input and output lines. The writing driver also consumes a certain amount of power whenever it operates.
In particular, recently, there has been an increasing demand for a semiconductor memory device having a large bandwidth, i.e., a large amount of input and output (IO) data transmitted per unit time, with the development of multimedia applications. Accordingly, semiconductor memory devices having high bandwidths of X16, X32, X64, etc. have been developed. This increase of the bandwidth increases the number of data output terminals, which consequently increases the number of input and output sense amplifiers and writing drivers. Therefore, the amount of power which is consumed by the input and output sense amplifiers and writing drivers is also increased.
SUMMARY OF THE INVENTION
In accordance with the present invention, a memory device is provided for reading and writing of data to a memory, the memory device comprising an input and output sense amplifier for amplifying data read from a memory cell of the memory and transferred to an input and output line, and transferring the read data to a data output line; and a writing driver circuit for receiving write data via a data input line and transferring the received write data to the input and output line, wherein each of the input and output sense amplifier and the writing driver circuit operates only when previously-read or previously-written data is different from current data to be read or written.
In accordance with another aspect of the present invention, the memory device further comprises an input and output sense amplifier driving unit for generating an input and output sense amplifier driving signal to control the input and output sense amplifier such that the input and output sense amplifier is deactivated when previously read data on the data output line is the same as current read data on the input and output line, and to activate the input and output sense amplifier when the previously read data is different from the current read data; and a writing driver driving circuit for generating a writing driver driving signal for controlling the writing driver such that the writing driver is deactivated when previous write data on the input and output line is the same as current write data on the data input line, and generating a writing driver driving signal to activate the writing driver when the previous write data is different from the current write data.
In accordance with a further aspect of the present invention, a memory device is provided which transfers data read from a selected memory cell to an input and output line and outputs the data via a data output line, the device comprising: an input and output sense amplifier which amplifies data read from the memory cell and transfers the amplified data an output of the sense amplifier; a latch unit having an input coupled to the output of the sense amplifier for receiving and latching data received from the output of the sense amplifier, and providing the latched data to an output of the latch units; and an input and output sense amplifier driving unit coupled to the input and output line and to the latch unit for comparing previously read data on the data output line with current read data on the input and output line, and generating an input and output sense amplifier driving signal for activating or deactivating the input and output sense amplifier as a function of the result of the comparison.
In the memory device according to the immediately preceding aspect of the present invention, the input and output sense amplifier driving signal is deactivated when the previous read data on the data output line is the same as the current read data on the input and output line, and activated when the previous read data is different from the current read data.
In accordance with another aspect of the present invention, a memory device is provided which transfers write data, which is received from an external source via a data input line, to an input and output line, and writes the write data to a selected memory cell, the device comprising: a writing driver which transfers the write data received via the data input line, to the input and output line; and a writing driver driving unit which compares the write data on the data input line with the write data on the input and output line, and generates a writing driver driving signal for controlling the writing driver, wherein the writing driver operates only when previous write data is different from current write data.
In another aspect, in the memory device according to the immediately preceding aspect, the writing driver driving signal is deactivated when previous write data on the input and output line is the same as current write data on the data input line, and activated when the previous write data is different from the current write data.
According to a further aspect of the present invention, a data reading/writing method is provided for a memory device including an input and output sense amplifier for amplifying data which has been read from a memory cell and transferred to an input and output line, and transferring the resultant data to a data output line, and a writing driver for receiving write data via a data input line and transferring the received write data to the input and output line, the method comprising the steps of: (a) comparing previously-read data on the data output with current read data, which is on the input and output line, and comparing previously-written data on the input and output line with current data to be written which is on the data input line; and (b) generating a control signal for enabling or disabling the input and output sense amplifier and the writing driver as a function of the results of the comparison.
Additionally, in another aspect of the present invention, in the above method the control signal is deactivated when the previously-read/written data is the same as the current data to be read/written, and activated when the previously-read/written data is different from the current data to be read/written.
REFERENCES:
patent: 5363330 (1994-11-01), Kobayashi et al.
patent: 5684750 (1997-11-01), Kondoh et al.
patent: 5710736 (1998-01-01), Masuda et al.
patent: 6031785 (2000-02-01), Park et al.
patent: 6122203 (2000-09-01), Hunt et al.
Elms Richard
Heid David W.
Nguyen Hien
Samsung Electronics Co,. Ltd.
Skjerven Morrill & MacPherson LLP
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