Abstract: A semiconductor flash memory includes an erase/write control unit that, when performing an erase/write operation of read memory cells, reads and senses memory current of the read memory cells for each memory cell, and adjusts threshold voltage of each of the read memory cells to a predetermined value, and a readout control unit that, when performing a read operation, selects at least two read memory cells simultaneously from among the read memory cells to which the erase/write control unit stored the same data, and senses total memory current for the at least two read memory cells.

Abstract: At the time of an operation of writing data to a specific memory cell in a memory block, a semiconductor memory device applies a write voltage for a predetermined period and, after that, performs a verifying operation by using a sense amplifier circuit and a comparator. When it is found as a result of the verifying operation that writing to the memory cell is insufficient, the writing operation is performed again by an instruction of a memory control circuit. At this time, the memory control circuit adjusts a write voltage.

Abstract: N-channel MOS transistors in a read gate circuit have respective sources connected to a sense amplifier activation line of a sense amplifier, not to a ground node. A read column selection line is selected prior to activation of the sense amplifier. Accordingly, paired read data lines are driven simultaneously with the activation of the sense amplifier.

Abstract: The clock-generating circuit for generating a clock signal, includes a ring oscillator having an odd number of inverters connected in a ring configuration. The ring oscillator is activated to generate a clock signal when an activating signal is at a first level and is de-activated to cease generation of the clock signal when the activating signal is at a second level. A latch circuit is connected to an output node of the ring oscillator, and holds a level of the output node of the ring oscillator in response to transition of the activating signal from the first level to the second level. When the activating signal is lowered from the H level to the L level, the level of the clock signal is latched such that generation of a glitch in the clock signal will be prevented from occurring.

Abstract: A VDC circuit that supplies an internal voltage VDD1 to an internal circuit in a normal operation forces a transistor off in a burn-in test mode through input of a test signal to suppress supply of an external power supply voltage VDDH to a node. In a burn-in test mode, an external power supply voltage lower than external power supply voltage VDDH and higher than internal voltage VDD1 is supplied from an external pad.

Abstract: With power-on detection circuits provided for a plurality of power supply voltages, a main power-on detection signal is maintained at the active state to reset an internal node while at least one of the power-on detection signals is active. In a multi-power semiconductor integrated circuit device, current consumption at the time of power-up is reduced.

Abstract: N-channel MOS transistors in a read gate circuit have respective sources connected to a sense amplifier activation line of a sense amplifier, not to a ground node. A read column selection line is selected prior to activation of the sense amplifier. Accordingly, paired read data lines are driven simultaneously with the activation of the sense amplifier.

Abstract: Oscillation outputs which are different for respective detector signals output from a first detector circuit and a second detector circuit, are obtained from a first ring oscillator and a second ring oscillator respectively corresponding to the detector circuits. A selector selects and outputs one of the oscillation outputs. Accordingly, it is sufficient to provide only one pump circuit in a circuit producing a substrate bias voltage.

Abstract: A tuning control circuit includes fuse devices each shifting from a conductive state to an interrupted state in response to a program input from the outside, and signal driving circuits for driving the signal levels of tuning control signals in accordance with the states of the fuse devices. A reference voltage generating circuit generates a reference voltage corresponding to a reference value of a memory array voltage of a semiconductor memory device according to the invention in accordance with an electrical resistance value which is finely adjusted in response to the tuning control signals.

Abstract: At the time of an operation of writing data to a specific memory cell in a memory block, a semiconductor memory device applies a write voltage for a predetermined period and, after that, performs a verifying operation by using a sense amplifier circuit and a comparator. When it is found as a result of the verifying operation that writing to the memory cell is insufficient, the writing operation is performed again by an instruction of a memory control circuit. At this time, the memory control circuit adjusts a write voltage.

Abstract: This DRAM includes a driver circuit which is provided to be common to a plurality of columns and which lowers level of one of selected first and second bit lines to “L” level in accordance with potentials of first and second write data lines. Therefore, as compared with a conventional DRAM in which a driver circuit is provided for each column, the number of transistors is decreased and a layout area is reduced.

Abstract: In a detector included in a VPP generating circuit in a DRAM, an external power supply potential is applied to the gate of an N-channel MOS transistor for regulating a through current of an inverter for outputting an inversion signal of an output signal of a comparator. Since a drain-source voltage of the N-channel MOS transistor can be set to be lower than a threshold voltage Vthn of the N-channel MOS transistor, an operation margin of the detector under conditions of a low voltage and a low temperature is made wider as compared with a conventional technique.

Abstract: A DRAM is provided at a portion relating to generation of a boosted potential with a filter circuit located between a detector circuit and a ring oscillator for removing a pulse-like change in level from an output signal of the detector circuit. Accordingly, temporary stop of the charge pump circuit can be prevented even when the boosted potential exceeds in a pulse-like manner the reference potential at the vicinity of the output node of the charge pump circuit, and the boosted potential can be rapidly restored to the reference potential.

Abstract: This DRAM includes a driver circuit which is provided to be common to a plurality of columns and which lowers level of one of selected first and second bit lines to “L” level in accordance with potentials of first and second write data lines. Therefore, as compared with a conventional DRAM in which a driver circuit is provided for each column, the number of transistors is decreased and a layout area is reduced.

Abstract: The clock generating circuit includes: an oscillator generating a reference clock signal; an EX-OR gate connected in a ring configuration; and first and second D latch circuits. The EX-OR gate inverts a clock signal to provide the inverted clock signal to the first D latch circuit when an activating signal is at H level. In this case, the clock signal is a clock signal having a clock cycle period of twice that of the reference clock signal. The EX-OR gate provides the clock signal direct to the first D latch circuit when the activating signal is set to L level. In this case, level transition of the clock signal is ceased. Hence, generation of a glitch in the clock signal is prevented from occurring.

Abstract: A DRAM is provided at a portion relating to generation of a boosted potential with a filter circuit located between a detector circuit and a ring oscillator for removing a pulse-like change in level from an output signal of the detector circuit. Accordingly, temporary stop of the charge pump circuit can be prevented even when the boosted potential exceeds in a pulse-like manner the reference potential at the vicinity of the output node of the charge pump circuit, and the boosted potential can be rapidly restored to the reference potential.

Abstract: In a VDC circuit, a differential amplifier compares a first reference potential with an internal supply potential to generate a control signal according to a result of the comparison. A constant current source transistor receives at its gate a second reference potential supplied through a path different from that of the first reference potential to operate for controlling an operation current value of the differential amplifier. A drive transistor changes conductance between a node for outputting the internal supply potential and a supply potential according to the control signal.

Abstract: A VDC circuit that supplies an internal voltage VDD1 to an internal circuit in a normal operation forces a transistor off in a burn-in test mode through input of a test signal to suppress supply of an external power supply voltage VDDH to a node. In a burn-in test mode, an external power supply voltage lower than external power supply voltage VDDH and higher than internal voltage VDD1 is supplied from an external pad.

Abstract: A tuning control circuit includes fuse devices each shifting from a conductive state to an interrupted state in response to a program input from the outside, and signal driving circuits for driving the signal levels of tuning control signals in accordance with the states of the fuse devices. A reference voltage generating circuit generates a reference voltage corresponding to a reference value of a memory array voltage of a semiconductor memory device according to the invention in accordance with an electrical resistance value which is finely adjusted in response to the tuning control signals.

Abstract: A capacitor (C12) is connected between a node (L) in a double boost part and the ground, and the amplitude of a repetitive pulse from the node (L) is made less than twice that of the power-supply voltage through utilization of charge and discharge of the capacitor (C12).