Fujitsu Corporation

Fujitsu Microelectronics Limited

Masato Takita

Masato Matsumiya

Ayako Kitamoto

Kuninori Kawabata

Toru Koga

Satoshi Eto

Toshikazu Nakamura

Hideki Kanou

Shinichi Yamada

Yuki Ishii

Masatomo Hasegawa

Kaoru Mori

Mitsuhiro Higashiho

Toshimi Ikeda

Hideki Kano

Atsushi Hatakeyama

Koichi Nishimura

Masao Taguchi

Yoshinori Okajima

Hirohiko Mochizuki

Tadao Aikawa

Shusaku Yamaguchi

Yuichi Uzawa

Junji Ogawa

Akira Kikutake

Satoru Saitoh

A semiconductor device, including a word line driver for driving a word line connected to a memory cell in a memory cell array and for resetting the word line when the memory cell changes from an activated to a standby state. The reset level of the word line driver is set when resetting of the word line is performed, and may be switched between first and second potentials. A word line reset level generating circuit varies the amount of negative potential current supply in accordance with memory cell array operating conditions. The semiconductor device includes a plurality of power source circuits, each having an oscillation circuit and a capacitor, for driving the capacitor via an oscillation signal outputted by the oscillation circuit. At least some power source circuits share a common oscillation circuit, and different capacitors are driven via the common oscillation signal.

Semiconductor memory device capable of driving non-selected word lines to a variable negative potential based on a bank access operation

A shift register includes plural latches corresponding to normal word lines of normal memory cell rows and a redundancy word line of a redundancy memory cell row, respectively, in order to sequentially activate any of the redundancy word line and the normal word lines upon every refresh request. An activation circuit activates any of the normal word lines and redundancy word line according to an output of the shift register. A first storing circuit stores in advance a defect address indicating a defective normal memory cell row. A first activation control circuit prohibits activation of a normal word line corresponding to the defect address stored in the first storing circuit when the output of the shift register indicates the normal word line.

Semiconductor memory

A semiconductor device includes a word line drive circuit for resetting the word line by driving the word line connected to a memory cell and is constituted so as to switch a reset level of the word line drive circuit, which is set at the time of the reset operation of the word line, between a first potential such as a ground potential and a second potential such as a negative potential. Further, a semiconductor device including a memory cell array formed by arranging a plurality of memory cells and a word line reset level generating circuit for generating a negative potential makes it possible to vary the amount of a current supply of the word line reset level generating circuit when non-selected word lines are set to a negative potential by applying the output of the word line reset level generating circuit to the non-selected word lines, and varies the amount of the current supply of the negative potential in accordance with the operation of the memory cell array. Furthermore, in a semiconductor device including a plurality of power source circuits each having an oscillation circuit and a capacitor, for driving the capacitor by the oscillation signal outputted by the oscillation circuit, at least a part of these power source circuits shares in common the oscillation circuit, and different capacitors are driven by the oscillation signal outputted from the common oscillation circuit.

Semiconductor device

A semiconductor memory device includes a plurality of word decoders arranged in a plurality of columns, a plurality of word line selecting shift registers corresponding to the respective word decoders to indicate a word line subjected to refresh operation, and a shift control signal generating circuit operable to supply a shift control signal indicative of timing of shift operations to the plurality of word line selecting shift registers, wherein the said shift control signal generating circuit is configured to supply the shift control signal only to a column currently subjected to refresh operation among the plurality of columns.

Semiconductor memory device with reduced power consumption for refresh operation

A semiconductor memory device includes a plurality of bit line pairs, each of which includes a first bit line and a second bit line, a plurality of memory cells which are coupled to said first bit line, and store electric charge in capacitors, a dummy cell which is coupled to a second bit line, and is charged with a predetermined potential, a sense amplifier which amplifies a potential difference between the first bit line and the second bit line, and a control circuit which charges said dummy cell with the predetermined potential only for a fixed time period.

Semiconductor memory device based on dummy-cell method

A plurality of switching transistors is provided, each connects power supply terminals of a plurality of first circuit blocks to a power supply line, respectively. Among the first circuit blocks, the power supply terminals of the first circuit blocks operating at different timings are connected by an internal power supply line. A power supply control circuit simultaneously turns on the switching transistors connected to the internal power supply line, in response to operation(s) of at least any one of the first circuit blocks connected to the internal power supply line. Since the switching transistors can be shared among the first circuit blocks not operating simultaneously, operation speed of the first circuit blocks can be increased. Since a total size of the switching transistors can be made small, standby current can be decreased. Accordingly, a semiconductor integrated circuit operating at a high speed can be constituted without increasing the standby current.

Semiconductor integrated circuit

A semiconductor device includes a word line drive circuit resetting the word line by driving the word line connected to a memory cell and switching a reset level of the word line drive circuit at the time of the reset operation of the word line. Further, a semiconductor device includes a memory cell array formed by arranging a plurality of memory cells and a reset level switch circuit for selecting a first potential or a second potential and supplying the first potential or the second potential to the word line drive circuit.

Semiconductor memory device capable of driving non-selected word lines to first and second potentials

A semiconductor integrated circuit, comprising a circuit unit having a predetermined function such as a level shifter circuit or a driver transistor circuit by a combination of a plurality of transistors, is disclosed. Among a plurality of the transistors of the circuit unit, the source potential of at least one transistor adapted to turn off during the standby period of the circuit unit is changed. Preferably, the semiconductor integrated circuit is configured to reduce the sub-threshold current flowing between the source and the drain of at least one transistor adapted to turn off during the standby period of the circuit unit by changing the source potential at a timing based on the standby period of the circuit unit in such a manner that a predetermined bias voltage is applied between the gate and the source of the transistor. A method of switching the source potential of at least one transistor in the semiconductor integrated circuit having the configuration described above is also disclosed.

Semiconductor integrated circuit and method of switching source potential of transistor in semiconductor integrated circuit

A first transistor is turned on during operation of a circuit block, to connect a substrate of the transistor to a first substrate voltage line. A second transistor is turned on during non-operation of the circuit block, to connect the substrate of the transistor to a second substrate voltage line. ON resistance of the second transistor is higher than that of the first transistor. A source-to-substrate voltage of the transistor being not in operation is set to be higher than that of the transistor being in operation. When a semiconductor integrated circuit switches from the operation state to the non-operation state, its substrate voltage changes gradually to a second substrate voltage. Charging/discharging currents of the substrate voltage can be dispersed so that it is possible to suppress current consumption in shifting from the operation state to the non-operation state and reduce a standby current in the non-operation state.

In the semiconductor memory, a refresh signal is generated and the refresh operation is performed based on the refresh signal. Parity is generated when data is written and the generated parity is stored. When the refresh operation and a usual data read or write operation overlap, data in a memory cell which cannot be read because the refresh operation is given priority is determined based on the parity. Data which cannot be written because the refresh operation is given priority is held temporarily in a write data buffer. When the refresh operation is not overlapped for the usual data read or write operation, the data held in the write data buffer is rewritten in a corresponding memory cell.

Semiconductor memory, and memory access method

A semiconductor memory selects desired one of word lines, which belong to banks each including a memory cell array, on the basis of a main WD select signal (mwd) and sub-WD select signals (swdx and swdz) determined in accordance with an address. The main WD select signal is a pulse signal. A latch circuit latches, for a predetermined time, the state of the sub-WD select signals having changed on the basis of state changes of the main WD select signal. This allows the banks to share the main WD select signal. Since a main WD signal generator is thus shared by the banks, the area of a chip can be reduced.

A variable delay circuit includes a first gate having a first delay amount, and a second gate having a second delay amount greater than the first delay amount. A difference between the first delay amount and the second delay time is less than the first delay amount.

Variable delay circuit and semiconductor integrated circuit device

A power supply line is formed over a memory cell array which has arranged a plurality of memory cells using a metal wiring layer M1 which is disposed on the side closest to the memory cell array, of all the metal wiring layers. The power supply lines are formed over the memory cell array using not only an upper metal wiring layer M2 but the metal wiring layer M1 so that the wiring resistance of the power supply lines may decrease and a sufficient amount of current can be supplied to the power supply lines. Consequently, the circuits supplied with an electric current through the power supply lines become capable of high-speed operation. This is particularly effective for the high-speed operation of the circuits arranged around the memory cell array. The power supply line formed using the lower metal wiring layer M1 is connected over the memory cell array to a power supply line which is formed using the metal wiring layer M2 on the upper layer than the metal wiring layer M1. Therefore, the netlike configuration of the power supply lines can be made with higher density compared to conventional ones.

Connections of global data buses GDB,and GDB,to local data buses LDB,to LDB,in a bank,are reverse to those in a bank,. That is, the global data bus GDB,is connected to every other local data bus LDB,, LDB,and LDB,including both sides in the bank,, and to every other local data buses LDB,and LDB,excluding both sides in the bank,, while the global data bus GDB,is connected to every other local data buses LDB,and LDB,excluding both sides in the bank,, and to every other local data bus LDB,, LDB,and LDB,including both sides. Further, bit line patterns obliquely traversing sense amplifier rows are reverse to each other with respect to the banks,and

Semiconductor memory device having multi-bank and global data bus

To reduce current consumption, there is provided a circuit for each bank, comprising selection circuits,through,each for selecting either a normal supply voltage Vii or a higher supply voltage Vjj as a supply voltage VH,in response to a selection control signals SC,and *SC,a selection control circuit,for generating the signals SC,and *SC0 to make the selection circuits select Vii when a bank activation signal BRAS,is inactive and Vjj for a predetermined period in response to activation of BRAS,and sense amplifier driving circuits,through,for supplying the ground voltage and VH,to the sense amplifier rows in response to activation of sense amplifier control signals. To stabilize the output voltage Vii of the power supply circuit having a NMOS transistor, the drain electrode, gate and source electrodes of which are at VCC, VG and approximately Vii&equals;VG&minus;Vth, where Vth is the threshold voltage of the NMOS transistor,a leak circuit is employed. The leak circuit has a NMOS transistor connected between Vii and ground. Wasteful power consumption by the current flowing to the leak circuit is negligibly small, e.g. 1 to 10 &mgr;A, and the variation of the supply voltage Vii reduces effectively.

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Kawasaki, Japan

Masato Takita