Kabushiki Kaisha Toshiba

Tokyo Shibaura Denki Kabushiki Kaisha

Microcomputer Engineering Ltd.

Takayuki Ohtani

Mitsuo Isobe

Tetsuya Iizuka

Masataka Matsui

Takayasu Sakurai

Jun-ichi Tsujimoto

Akira Aono

Hiroshi Iwai

Shigeyuki Hayakawa

Kazuhiro Sawada

Nobuaki Urakawa

During a data-clearing operation, while maintaining in the OFF state the transfer gate transistors in each of the static type memory cells associated with at least one column, the source of one of two drive transistors incorporated in the memory cell is set to a high potential level, and the source of the other drive transistor to a low level. As a result, the clearing operation is performed to a minimum of 1 column in the memory cell matrix. Due to the arrangement of the memory device, no address-selecting operation is required for selecting a memory cell during the clearing operation. Moreover, the clearing operation is carried out in a minimum unit of 1 column in the memory cell matrix. Consequently, the processing time for the clearing operation is reduced. Furthermore, the DC current flowing during the clearing operation is reduced, since the transfer gate transistor in the memory cell is maintained in the OFF state during the clearing operation, with the result that the power consumption is lowered.

Semiconductor memory device with a potential level-setting circuit

A precharge circuit is provided between bit lines, on the one hand, and a power source potential on the other. The precharge circuit is controlled to be conductive/nonconductive by a clear signal. A control unit is also provided, which controls a decoder when the clear signal is supplied so as to set all the word lines in a selective state. In a clear mode, writing circuits write the same data simultaneously into all of the memory cells.

Semiconductor memory device

In a semiconductor memory device with normal word lines and spare word lines, a partial decoder receives and decodes a predetermined two of the bit signals of the original logic levels of an address signal, and two of the bit signals of the complementary logic levels, which correspond to the predetermined two bit signals, and outputs different signal combinations of the predetermined two bit signals and the two corresponding bit signals. A spare word line selecting circuit receives the different signals and selects one of the different signals in order to select a spare word line which corresponds to a normal word line to which a defective cell is connected. The partial decoder may be used for both the normal word line selection and the selection of spare word lines. With a device constructed in such a manner, bit signals of an address signal are not directly input to the spare word line selecting circuit, but rather signals of different bit signal combinations are input to it. The spare word line selecting circuit merely selects signals of different combinations, and does not need the partial decoding of the address signal. Therefore, the chip area required for wiring may be remarkably reduced when compared with the conventional memory device.

Semiconductor memory device using partial decoders for redundancy

In a selected column, a pull-up transistor pair is not selected but, instead, a transmission gate transistor pair is selected. In the read mode, the transmission gate transistor pair serves as pull-up loads between the bit line pair. However, the transmission gate transistor pair is kept off until the voltage across the bit line pair is decreased from the power supply potential level to the threshold voltage level of the transmission gate transistors. Therefore, no DC current path is formed in the bit line pair when the voltage across the bit line pair is within a range from a voltage equal to the power supply potential level to a potential lower than the power supply potential by an amount equal to the threshold voltage level, and the rate of increase of a potential difference across the bit line pair is determined by a pull-in current of the memory cell. Therefore, a high-speed sense operation can be realized. In the write mode, the transmission gate transistor pair serves a bit line pull-up function. Since no normally-ON bit line load transistor is arranged, no direct current path including the bit line pair is present, and hence, low power consumption can be achieved.

Static memory using a MIS field effect transistor

The threshold voltage of bit line percharge/equalize MOS transistors is smaller than that of normally ON type bit line pull-up transistors. With this feature, there is no current flows through a bit line from power source V.sub.DD during a read-out operation. The voltage difference between a pair of bit lines can be increased at high speed, thereby increasing the read-out speed.

Static memory with pull-up circuit for pulling-up a potential on a bit

Voltage converters are arranged in units of columns in a memory device. Each voltage converter is connected to a column decoder. The column decoder receives a column address signal and supplies a column selection signal to the voltage converter. The voltage converters apply a ground level voltage to the source junctions of the drive transistor pairs of the memory cells of the selected columns, and a voltage higher than the ground level voltage to the source junctions of the drive transistor pairs of the memory cells of the nonselected columns so as to decrease power consumption in the nonselected columns as compared with that in the selected columns.

MOS static memory circuit

A static memory has an address transition detector, an input data transition detector and a pulse signal generator. When a detector detects that an input address or input data has changed, the pulse signal generator produces a pulse signal having a width longer than the shorter of the data-reading or data-writing cycle. This pulse signal controls the period of time during which a penetrating DC current flows between two power sources via some of the components of the memory.

Static memory utilizing transition detectors to reduce power consumption

A memory cell array consists of a plurality of memory sections. A pair of bit lines are provided for each column, and word lines are provided each for each row in each memory section. One end of the current path of a first transistor is connected to the corresponding bit line. A predetermined voltage is applied to the other end of the current path of the first transistor. One end of the current path of a second transistor is connected to the corresponding bit line. A predetermined voltage is applied to the other end of the current path of the first transistor. The current capacity of the first transistor is larger than that of the second transistor. After an address signal varies and a predetermined period elapses, the first transistor in the selected section turns on, the second transistor in the selected section turns off, the first transistor in the nonselected section turns off, and the second transistors in the nonselected section turns on. The bit lines in the selected section are charged for a predetermined period of time after the address signal changes, to pull up the voltages of the bit lines in the nonselected section to a power supply voltage. A row decoder renders the word line active in level after the first transistor connected to the bit lines of the selected section is turned off according to an address signal.

Static semiconductor memory device

There is disclosed a sense amplifier characterized by comprising a pull-up circuit. The pull-up circuit comprises a first transistor arranged between the first of a pair of output nodes and a pull-up power source potential node, and a second transistor arranged between the second of the pair of output nodes and the pull-up power source potential node. The gate of the first transistor is connected to the second output node and the gate of the second transistor is connected to the first output node.

Current-mirror type sense amplifier

A signal input circuit particularly well suited for use in MOS integrated circuits. The signal input circuit includes: and input gate circuit for receiving an input signal and an enable control signal, and for generating an output signal equal to the input signal when the enable control signal is in an 'enable' state, and for providing a high output impedance when the enable control signal is in a 'disable' state; and a holding circuit coupled to an output of the input gate circuit and to receiving the enable control signal, for holding, during the disable state, the output state of the input gate circuit immediately before the enable control signal changes to a disable state, the output impedance being high when the enable control signal is in an enable state.

Low power consumption, high speed CMOS signal input circuit

In the semiconductor memory device according to the present invention, when there is a defective portion in the memory cells, those memory cells are replaced by redundant memory cells. When defective portions are discovered in the memory cells, the fuse elements corresponding to the memory cells having the defective portions are cut off. Voltages of the select lines connected to the memory cells having the defective portions are held at an L level by the resistors. Due to this, the memory cells having the defective portions are not selected.

A transition detector circuit comprises a first invertor train comprising 2n stages of invertors (n: positive integer including zero), the input thereof being connected to a signal input terminal while the output thereof is connected to an in-phase output terminal, a second invertor train comprising 2n+1 stages of invertors, the input thereof being connected to the signal input terminal, while the output thereof is connected to an antiphase output terminal, a third invertor train comprising at least one stage of an invertor, which is connected to the output of the first invertor train, a fourth invertor train, comprising at least one stage of an invertor, which is connected to the output of the second invertor train, and a fifth invertor train comprising at least one stage of an invertor, which is connected to the signal input terminal. The transition detector circuit further comprises a first switching circuit which turns on or off in response to a signal fed from the third invertor train to produce a pulse signal having a first delay time determined by the first and third invertor trains, and a second switching circuit which turns on or off in response to a signal fed from the fourth invertor train and turns off or on in response to a signal fed from the fifth invertor train to produce a pulse signal having a second delay time determined by the second, fourth and fifth invertor trains.

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Tokyo, Japan

Takayuki Ohtani