Abstract: A semiconductor memory device is disclosed. A block unit is divided into memory mats based on an internal address. In the case where the internal address is “1”, data are read in ascending order in accordance with a start address from the memory mat, while the internal address is incremented by an address conversion circuit thereby to select a 4-word block including the words next selected from the memory mat. At the same time, the internal address is incremented based on the start address, so that the period for reading each word included in the lowest order of 4-word block can be secured. In the process, the address next to be input can be decoded.

Abstract: An external clock generating circuit generates a mode indicating signal at the “H” level and generates an external clock signal synchronized with a write command buffer signal, when a semiconductor memory device is not in an internal operation mode. When the semiconductor memory device enters an internal operation mode and the mode indicating signal makes a transition from “H” to “L”, the external clock signal is fixed at the “L” level. The external clock signal is not supplied to an external CUI, and the external CUI is set in a state in which reception of any external command is prohibited. Until the end of asynchronous reset, the mode indicating signal is kept at the “L” level, and thereafter raised to the “H” level, so that malfunction caused by an input of an external command during asynchronous reset period can be avoided.

Abstract: A manner of generating internal voltages such as a high voltage, an intermediate voltage and an internal power supply voltage is switched in accordance with a power supply level setting signal. When the voltage level of an external power supply voltage is low, a current drive transistor receiving an output of a comparing circuit and an auxiliary drive transistor are forcedly set in a conductive state, and external power supply voltage is transmitted on an internal power supply line. At this time, the comparing operation of the comparing circuit is stopped. When the level of the external power supply voltage is high, the comparing circuit is activated down convert the external power supply voltage for generating a peripheral power supply voltage on the internal power supply line.

Abstract: If a region designated by an address signal is a logic control region, an interface portion transmits/receives data to/from a register instead of a DRAM. A data signal used at that time is a control command for a logic circuit held in the register or input data for a process in the logic circuit. Depending on the content held in the register, the logic circuit performs, for example, an encryption process or a process which takes for a microcomputer a long time to complete such as an image processing. The result of processing is stored in the register and read in a sequence of reading from the DRAM.

Abstract: Data pad regions are arranged in four divided regions of a semiconductor memory chip of a rectangular shape, respectively, and data pads are selectively utilized in each of the four divided regions in accordance with a word structure. Thus, it is possible to implement a semiconductor memory chip capable of being assembled in both a single chip package and a multi chip package.

Abstract: A semiconductor memory device is disclosed. A block unit is divided into memory mats based on an internal address. In the case where the internal address is “1”, data are read in ascending order in accordance with a start address from the memory mat, while the internal address is incremented by an address conversion circuit thereby to select a 4-word block including the words next selected from the memory mat. At the same time, the internal address is incremented based on the start address, so that the period for reading each word included in the lowest order of 4-word block can be secured. In the process, the address next to be input can be decoded.

Abstract: A multi-level semiconductor memory device for storing multi-level data having three or more values is implemented by utilizing a nonvolatile memory device for storing 2-valued data. Identification of successive 16-bit data externally applied is performed with external address bit AA [2], and a storage block is selected with external address bit AA [23]. Upper word data LW and lower word data UW are compressed into byte data of 8 bits; respectively, and stored in a memory cell array.

Abstract: A transistor is arranged for electrically isolating a sense amplifier formed of a thin film transistor from a data line electrically coupled to the sense amplifier. When a write driver drives the data line, a control signal is applied to isolate the data line from the sense amplifier.

Abstract: Until the number of pulse application n reaches 12, as a first-half pulse, a pulse is set to have a width fixed to 2 ms, and its voltage is increased every time. As a latter-half pulse, the pulse is set to have a width fixed to 3 ms and the pulse voltage is increased every time until the maximum voltage is attained. After the maximum voltage is attained, first, the pulse of a width of 3 ms is applied twice, the pulse of a width of 4 ms with the maximum voltage is applied twice, and the pulse of a width of 5 ms with the maximum voltage is applied twice. Even after the maximum voltage is attained, change over time of a threshold voltage can be more linear. Thus, a non-volatile semiconductor memory device allowing efficient programming operation and erasing operation in a short period of time can be provided.

Abstract: An external clock generating circuit generates a mode indicating signal at the “H” level and generates an external clock signal synchronized with a write command buffer signal, when a semiconductor memory device is not in an internal operation mode. When the semiconductor memory device enters an internal operation mode and the mode indicating signal makes a transition from “H” to “L”, the external clock signal is fixed at the “L” level. The external clock signal is not supplied to an external CUI, and the external CUI is set in a state in which reception of any external command is prohibited. Until the end of asynchronous reset, the mode indicating signal is kept at the “L” level, and thereafter raised to the “H” level, so that malfunction caused by an input of an external command during asynchronous reset period can be avoided.

Abstract: A memory array including memory mats is arranged in a U shape when seen in two dimensions, and a logic circuit and an analog circuit are arranged in a region unoccupied by the memory array. This facilitates transmission of power supply voltage and signals between the peripheral circuit including the analog and logic circuits and the pad band including power supply and data pads. The analog circuit is positioned close to the power supply pad, so that voltage drop due to the resistance of power supply interconnection is restricted. It is also possible to separate a charge pumping power supply interconnection and a peripheral circuit power supply interconnection in the vicinity of the power supply pad.

Abstract: In the present semiconductor device a positive, driving pump circuit is driven by an external power supply potential EXVDD (for example of 1.8V) to generate a positive voltage VPC (for example of 2.4V). A negative pump circuit for internal operation is driven by the positive voltage VPC to generate a negative voltage VNA (for example of ?9.2V) required in an erasure or similar internal operation for a word line. The negative pump circuit for internal operation can have a smaller number of stages of pump and hence consume a smaller area than when the circuit is driven by the external power supply voltage EXVDD (for example of 1.8V) as conventional.

Abstract: A reference cell is connected to two reference bit lines. In data access, when one reference bit line is driven to a selected state in response to a reference column select signal which is a decode result of a column address, a potential of a selected reference bit line is transmitted to a reference data bus line. A potential difference between the reference data bus line and a data bus line is amplified by a sense amplifier, and read data is output from an external terminal. During the access period, a reference bit line in a non-selected state is precharged to a ground potential in response to a reset signal at H level. In the next data access, when the non-selected reference bit line is selected, successive data reading is attained without waiting for a time period for precharging a bit line.

Abstract: The semiconductor memory device includes a refresh timer for determining a refresh cycle of self-refresh operation. The refresh timer includes a voltage regulator, a ring oscillator and a counter. The voltage regulator generates a bias voltage having positive temperature characteristics. The ring oscillator varies an oscillation cycle of a pulse signal according to the bias voltage. The counter counts a prescribed number of pulse signals and generates a refresh signal for executing refresh operation. The semiconductor memory device thus varies the refresh cycle according to a temperature change, and executes refresh operation with an appropriate refresh cycle.

Abstract: A reference cell is connected to two reference bit lines. In data access, when one reference bit line is driven to a selected state in response to a reference column select signal which is a decode result of a column address, a potential of a selected reference bit line is transmitted to a reference data bus line. A potential difference between the reference data bus line and a data bus line is amplified by a sense amplifier, and read data is output from an external terminal. During the access period, a reference bit line in a non-selected state is precharged to a ground potential in response to a reset signal at H level. In the next data access, when the non-selected reference bit line is selected, successive data reading is attained without waiting for a time period for precharging a bit line.

Abstract: An input circuit includes a gate circuit receiving an output power supply voltage that determines the logic level of an input signal or a comparison circuit receiving an input signal and a reference voltage depending on the output power supply voltage supplied from a pad different from a power supply pad for an output circuit.

Abstract: A row address decoder of a semiconductor memory device generates internal row address signals RAD<0:11> and /RAD<0:11> by switching most significant bit and least significant bit of row address signals RA<0:11> and /RA<0:11> that correspond to address signals A0 to A11, respectively. In a twin cell mode, the least significant bits RAD<0> and /RAD<0> of the internal row address signals corresponding to the most significant bits RA<11> and /RA<11> of the row address signal that are not used are selected simultaneously by row address decoder, and two adjacent word lines are activated simultaneously. Consequently, the configuration of memory cell in the semiconductor memory device can electrically be switched from the normal single memory cell type to the twin memory cell type.

Abstract: A refresh array activating signal is activated in accordance with a refresh request and specific address bit(s) of a refresh address. Specific lower bit(s) of a refresh address counter is (are) utilized as the specific address bit(s) of the refresh address, and the specific address bit(s) is (are) utilized as upper bit(s) of the refresh address. Thus, in the self-refresh mode, refresh can be performed for a prescribed address region at uniform intervals, with a lengthened refresh interval, consuming less current. A semiconductor memory device is provided which allows current consumption to be distributed on a time basis and to be reduce in a self-refresh mode is provided.

Abstract: In the output circuit, at a subsequent stage of a gate circuit operating with a power supply voltage related to a first power supply voltage, a latch circuit formed of an inverter circuit and a MOS transistor is arranged, and is supplied with a second power supply voltage as an operating power supply voltage. An output buffer circuit is driven in accordance with an output signal of the latch circuit. When the first power supply voltage is powered down, the latch circuit receiving and operating with the second power supply voltage holds a signal voltage to be attained in a standby state and thus the output buffer circuit is reliably held in an output high impedance state. In a semiconductor device of a double power supply configuration, even when one power supply is powered down, the output buffer circuit can reliably be set to an output high impedance state.

Abstract: A bias voltage having a positive temperature dependency is supplied to a current source that determines the operating current of a refresh timer that issues a refresh request to allow the driving current of the current source to have a positive temperature characteristic. In this manner, the refresh cycle of the refresh timer shortens the issue intervals when the temperature rises, and lengthens the issue intervals of the refresh request when the temperature decreases. Thus, the consumed current for the refresh at room temperature is reduced. Consequently, the consumed current in a self-refresh mode under the room temperature condition can be reduced.