Fujitsu Corporation

Fujitsu Microelectronics Limited

Masatomo Hasegawa

Masato Matsumiya

Masato Takita

Satoshi Eto

Kuninori Kawabata

Toshikazu Nakamura

Ayako Kitamoto

Toru Koga

Hideki Kanou

Yuki Ishii

Shinichi Yamada

Kaoru Mori

Toshimi Ikeda

Akira Kikutake

Satoru Saitoh

Masaaki Higashitani

Yuichi Uzawa

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 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 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 memory device is provided with a clock generation circuit that generates a first clock that has the same frequency and phase as an external clock, and a second clock that has the same frequency as the external clock but a phase a quarter phase shifted, and the first clock and the second clock are supplied to the two DDR-DRAMs as clocks so that the two DDR-DRAMs can operate in a state of being a quarter phase shifted from each other. A data output section outputs data respectively for time periods corresponding to a quarter phase from points a fixed phase behind the leading edge and the trailing edge of the first or the second clock and brings a data output circuit into a high impedance state for other time periods.

Semiconductor memory device

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

According to a semiconductor memory for one aspect of the present invention, a memory cell transistor is formed in a P-type first well region which is formed at the surface of a P-type semiconductor substrate, and a back bias voltage is applied to the P-type first well region and the P-type substrate. Further, an N-type retrograde region is formed by implanting a high energy N-type impurity, so that a deeper, N-type second well region is formed by employing the N-type retrograde region. Further, a P-type third well region is formed in the N-type second well region, and a P-type emitter region is also formed therein. Thus, together the P-type emitter region, the N-type second well region, and the P-type third well region constitute a lateral PNP transistor. In addition, the ground voltage is maintained for the P-type third well region, which serves as a collector region.

Segment selection circuits,A are arranged adjacent read/write amplifiers,. When one of the segments,to,in a memory cell array,is selected by a signal on segment address lines CA,to CA,, a read amplifier,or a write amplifier,of the read/write amplifier,corresponding to the selected segment is activated in response to activation of a signal on a read timing signal line RT or a write timing signal line WT. The lines CA,to CA,, RT and WT are arranged along the row of the segment selection circuits,A.

Semiconductor memory device having read/write amplifiers disposed for respective memory segments

A semiconductor device having the function of generating an internal clock signal delayed by a predetermined phase by adjusting the phase of an external clock signal, includes a first clock phase circuit for roughly adjusting the phase of the external clock signal; and a second clock phase adjusting circuit for controlling the phase of the internal clock signal with higher accuracy than the first clock phase adjusting circuit. The semiconductor device having such a construction executes phase comparisons by the first and second clock phase adjusting circuits independently of each other, and when a phase control operation by the second clock phase adjusting circuit is made subordinate to that of the first clock phase adjusting circuit, the delay time of each of a plurality of delay elements inside the first clock phase adjusting circuit is set to a value larger than a power source jitter resulting from a noise of a power source and a jitter of the external clock signal.

A semiconductor integrated circuit producing a given output voltage includes first and second operational amplifiers, and first and second transistors. The first and second operational amplifiers detect a voltage difference between a voltage applied to an input terminal and at least one reference voltage. The first and second transistors are turned ON or turned OFF according to the levels of voltages output from the first and second operational amplifiers. The first operational amplifier receives the output voltage at the input terminal. When the level of the output voltage becomes lower than the reference voltage, the first operational amplifier allows the first transistor to operate so as to raise the output voltage. In contrast, the second operational amplifier receives the output voltage at the input terminal. When the level of the output voltage exceeds the reference voltage, the second operational amplifier allows the second transistor to operate so as to lower the output voltage.

Semiconductor integrated circuit

On one hand, a row address is provided via a buffer gate to a row address register,, and its output is provided via a complementary signal generation circuit,and a predecoder,to a word decoder,A. On the other hand, in response to an issuance of-an activate command a control signal AS,is provided via a delay circuit,to the clock input CK of the row address register,as a strobe signal AS,, and AS,is provided, to reduce timing margin, via a delay circuit,A to the strobe signal input of the predecoder,as a strobe signal S,. S,is provided via a delay circuit,B to the strobe signal input of the word decoder,A having RS flip-flops,to,or latch circuits. Each of the latch circuits consists of a NOR gate having a set input and a reset input and another NOR gate having an input coupled to receive the output of the former NOR gate and another set input to receive a multiple selection signal which is common for all the latch circuits in word decoders.

Memory device having row decoder

A semiconductor device has a DLL circuit or the like for adjusting the phase of an external clock and producing an internal clock that lags behind by a given phase. The semiconductor device further includes a clock frequency judging unit for judging the frequency of a first clock on the basis of an indication signal indicating a delay value of the first clock in the DLL circuit or the like to output a control signal; and a clock selecting unit for selecting either one of the first clock and the second clock, in response to the control signal.

A semiconductor memory has memory cells arranged in arrays, direct-type sense amplifiers arranged in each column of the memory cells, for writing and reading data to and from a memory cell to be accessed, column selection lines for selecting sense amplifiers that are in a column that involves the memory cell to be accessed, write-only column selection lines for selecting sense amplifiers that are in a row that involves the memory cell to be accessed if the memory cell is accessed to write data thereto, and local drivers. The sense amplifiers are grouped, in each row, into sense amplifier blocks. The write-only column selection lines consist of first selection lines for selecting sense amplifier blocks that are in the row that involves the memory cell to be accessed for data write and second selection lines for selecting sense amplifiers that are contained in the selected sense amplifier blocks. The local drivers apply a selection signal to the second selection lines according to a selection signal from the first selection lines. The write-only column selection lines are controlled by signals that are used to control the sense amplifiers.

Semiconductor memory employing direct-type sense amplifiers capable of

The present invention relates to a memory device including memory cells each formed of a cell transistor connected to bit and word line and a cell capacitor. The memory device includes a pre-charging circuit for pre-charging bit line to a first voltage, a sense amplifier for detecting voltages of bit lines and driving the bit lines to a second voltage for H level or a third voltage for L level, and a word line driving circuit for driving word lines to make the writing voltage for H level of the cell capacitor to a fourth voltage lower than the second voltage. The present invention is characterized in that the first voltage is lower than an intermediate value between the second and third voltages. According to the present invention, it becomes possible to prevent the voltage V.sub.ds of the cell transistor from being zero by setting the writing voltage (fourth voltage) for H level of the cell capacitor to be lower than the voltage for H level (second voltage) of the bit line, thus reducing a time of writing or re-writing data. Additionally, a pre-charge voltage (first voltage) of the bit lines is set to be lower than the half of the amplitude of the bit line. Thereby, it also becomes possible to prevent the very small voltage of the bit line from being smaller according to the lowered H level voltage in the memory cell.

Memory device with faster write operation

On one hand, a row address is provided via a buffer gate to a row address register 11, and its output is provided via a complementary signal generation circuit 15 and a predecoder 16 to a word decoder 17A. On the other hand, in response to an issuance of an activate command a control signal AS1 is provided via a delay circuit 14 to the clock input CK of the row address register 11 as a strobe signal AS2, and AS2 is provided, to reduce timing margin, via a delay circuit 20A to the strobe signal input of the predecoder 16 as a strobe signal S2. S2 is provided via a delay circuit 20B to the strobe signal input of the word decoder 17A having RS flip-flops 2301 to 2332 or latch circuits. Each of the latch circuits consists of a NOR gate having a set input and a reset input and another NOR gate having an input coupled to receive the output of the former NOR gate and another set input to receive a multiple selection signal which is common for all the latch circuits in word decoders.

This invention is a memory device with a structure that has eliminated the logic circuit using I/O mask signal DQM from within the critical path from the clock CLK to the predecoder and column decoder for generating column selection signal CL. The logic circuit using I/O mask signal DQM within the critical path for generating column selection signals is eliminated, and the time from when the clock is supplied until the column selection signal is generated is made as short as possible. On the other hand, to make an I/O mask possible during burst write mode, drive control of the write amplifier is performed based on I/O mask signal DQM. Specifically, activation of the write amplifier is prohibited or allowed in response to the I/O mask signal DQM.

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Kawasaki, Japan

Masatomo Hasegawa