Abstract: A nonvolatile semiconductor memory system is provided with a nonvolatile memory cell array divided into erase blocks data and refresh blocks, and a flag cell array including a plurality of nonvolatile flag cells each of which corresponds to one of the refresh blocks and stores data representing the refresh status of the corresponding refresh block.

Abstract: In a flash memory EEPROM, a memory cell MC is formed in a P-type semiconductor substrate. A peripheral transistor TR is formed in an N-type well. Another peripheral transistor TR is formed in a P-type well. The P-type well is by turn formed an N-type well and electrically insulated from the substrate. The substrate is typically provided with a metal back structure and its substrate voltage is set to predetermined voltages respectively for data erasure, data storage and data retrieval. With such an arrangement, the level of voltage stress with which the device is loaded during data erasure can be remarkably reduced to allow a down-sizing and an enhanced quality to be realized for the device.

Abstract: A nonvolatile semiconductor memory device includes a row decoder circuit having first and second N-channel MOS transistors and first and second P-channel MOS transistors which correspond to each of word lines. One end of a source-to-drain current path of the first N-channel MOS transistor is connected to the word line, and the other end thereof is connected to a corresponding one of output terminals of a predecoder circuit. One end of a source-to-drain current path of the second N-channel MOS transistor is connected to the word line, and the other end thereof is supplied with a voltage of 0V or more in a data erase mode and is supplied with a low logical level signal in modes other than the data erase mode.

Abstract: A number of booster circuits to be operated out of a plurality of booster circuits are selected in accordance with a level of the boosted voltage to be provided at a common voltage output terminal of the plurality of booster circuits. With such an arrangement, fluctuations in the output voltage that can appear when a light load is applied to the voltage output terminal of the booster circuits can be effectively reduced to make the semiconductor memory device driven by the power supply circuit operate reliably. Further, one of the output terminals of intermediate voltage booster circuits is connected to the output terminal of a high voltage booster circuit. Then, a desired voltage can be obtained from the booster circuits that are implemented without using costly transistors to reduce the chip cost.

Abstract: A NOR type flash memory includes a plurality of word lines, a plurality of bit lines, at least one bit line, a plurality of nonvolatile memory cells, a row decoder, a cell selection circuit and a programming load. Each of the plurality of nonvolatile memory cells includes a gate electrode, drain electrode and source electrode and the gate electrode is connected to a corresponding one of the plurality of word lines, the drain electrode is connected to a corresponding one of the plurality of bit lines and the source electrode is connected to the source line. The row decoder selects one of the plurality of word lines at the time of data programming. The cell selection circuit includes a column decoder and column gates and is constructed to simultaneously select one bit line from each of the plurality of groups among the plurality of bit lines.

Abstract: A semiconductor circuit comprises an I-type of NMOS transistors N15 and N16 connected between a power supply voltage VDD and a ground electrode. The gate electrode of the NMOS transistor N15 is set to a reference voltage VREF that is lower than the power supply voltage VDD. The drain voltage VD of the NMOS transistor N16 is almost equal to the reference voltage VREF, and the NMOS transistor N16 acts in a linear region. Accordingly, the NMOS transistor N16 acts in the same manner as the resistor element and has no influence on change of the concentration of the diffusion resistor or the power supply voltage VDD.

Abstract: A nonvolatile memory semiconductor memory device is disclosed which incorporates fuse-cells in which data for setting a mode and redundancy data are stored. The nonvolatile memory semiconductor memory device incorporates a fuse-cell circuit including fuse-cells, a fuse-cell controlling circuit for reading data stored in the fuse-cell, a voltage boosting circuit for generating a boosted voltage and a voltage converting circuit which uses a reference voltage to convert the boosted voltage into read voltage for use when data is read from the fuse-cell. The reference voltage is generated by using a threshold voltage of a reference cell having the same structure as that of the fuse-cell.

Abstract: A nonvolatile semiconductor memory device is provided in which a negative voltage is applied to a gate electrode of a memory cell transistor during an erase mode. The memory device includes a row decoder circuit having an N-channel transistor connected to a word line. The N-channel transistor is provided on a P-type well region of a semiconductor substrate. A negative voltage is applied to the P-type well region during the erase mode, while ground potential is applied thereto during other modes.

Abstract: Each of first and second cell array groups has a cell array and a row decoder. Circuit blocks including a reset transistor, a Y selector, a write transistor, a block decoder, and a source decoder except the cell array and row decoder are arranged in the area between the first and second cell array groups. Since an address signal, a control signal, and a power supply common to the circuit blocks can be shared, the layout area can be reduced.

Abstract: A semiconductor integrated circuit device has a data storage section for storing mode setting data corresponding to products of a plurality of types, redundancy data, and so on. The redundancy storage section is made up of a nonvolatile transistor for storing the mode setting data corresponding to the products, the redundancy data, etc., a latch circuit for latching data read out from the nonvolatile transistor and generating a mode signal, and a transmission gate for transmitting the data from read out from the nonvolatile transistor to the latch circuit. The semiconductor integrated circuit device also has an internal voltage generator for generating an internal voltage. This internal voltage is used as the power supply voltage of the data storage section.

Abstract: In a booster circuit, a gate of an input-side transistor whose end is supplied with a power supply voltage is supplied with an inverted signal of a signal supplied to a signal input terminal of a booster unit at a first stage or supplied with an AND signal of the inverted signal and a booster circuit activation signal. Therefore, when the transistor at the first stage operates, the input-side transistor is turned off. Accordingly, a back flow of a current from inside the booster circuit to a power supply is prevented, so that the efficiency of the booster circuit can be improved. Further, fluctuations of the output voltage are not brought about even when the power supply voltage greatly fluctuates, so that the reliability of peripheral elements and memory cells can be improved and the allowable range of an external power supply voltage can be widened.

Abstract: A semiconductor integrated circuit device according to the present invention includes a booster circuit 1 for raising an external power supply voltage Vccext, a level detecting circuit 2 for detecting fluctuation in a stepped-up voltage Vccint2, an internal voltage generating circuit 3 for generating an internal voltage Vccint on the basis of the stepped-up voltage Vccint2, an address buffer 4, an address decoder 5, and a memory cell array 6 of an EEPROM structure. The level detecting circuit 2 includes a first level detecting part for performing level detection during a memory access state, and a second level detecting part for performing level detection during a stand-by state. During the stand-by state, the internal voltage generating circuit 3 short-circuits the stepped-up voltage Vccint2 and the internal voltage Vccint.

Abstract: A nonvolatile semiconductor memory device is provided in which a negative voltage is applied to a gate electrode of a memory cell transistor during an erase mode. The memory device includes a row decoder circuit having an N-channel transistor connected to a word line. The N-channel transistor is provided on a P-type well region of a semiconductor substrate. A negative voltage is applied to the P-type well region during the erase mode, while ground potential is applied thereto during other modes.

Abstract: A differential amplifier comprises an n-channel MOS transistor to the gate of which an input voltage VIN1 is fed, and an n-channel MOS transistor to the gate of which an input voltage VIN2 is fed. A p-channel MOS transistor arranged in such a manner that, to the source thereof, a power source voltage Vcc is fed, and the gate and drain thereof are connected to the drain of the MOS transistor, and a p-channel MOS transistor arranged in such a manner that the gate thereof is connected to the drain of the MOS transistor, the drain thereof is connected to the drain of the MOS transistor, and the voltage at this drain is outputted as an output voltage VOUT, and the output current I of a constant-current source is set so that the transistors constituting a differential amplifier may operate in a weak inversion zone.

Abstract: In a flash memory EEPROM, a memory cell MC is formed in a P-type semiconductor substrate. A peripheral transistor TR is formed in an N-type well. Another peripheral transistor TR is formed in a P-type well. The P-type well is by turn formed an N-type well and electrically insulated from the substrate. The substrate is typically provided with a metal back structure and its substrate voltage is set to predetermined voltages respectively for data erasure, data storage and data retrieval. With such an arrangement, the level of voltage stress with which the device is loaded during data erasure can be remarkably reduced to allow a down-sizing and an enhanced quality to be realized for the device.

Abstract: A semiconductor memory device is provided which incorporates a voltage generation circuit capable of generating a high voltage even when a low power voltage is applied to the device. To control the gate voltage of each cell included in a memory cell array, a negative voltage generating circuit connected to a row decoder is included in a boosting circuit. In the case of using a single power of a low voltage, the negative voltage generating circuit generates a negative high voltage during, for example, data erasing. The gate of each P-channel MOS transistor for data transfer is supplied with a pulse signal with an amplitude based on a voltage VCCH which is higher than an external power voltage VCC and obtained by boosting the voltage VCC. As a result, a high voltage can be transferred and output efficiently even if the external power voltage is low.

Abstract: The semiconductor integrated circuit device includes memory cells the conductive state of which is changed in accordance with the data stored therein when selected, a sensing circuit having sense nodes for sensing the data stored in the memory cell. A constant current source according to the present invention supplies a current corresponding to the leak current to be detected on the sense node, as a load current in a leak current check where the memory cell is set in a non-selected state and the leak current flowing through the memory cell is detected. Accordingly, the device can ensure a large reading margin even in checking the leak current flowing through the memory cell, prevent the increase in total area of the integrated circuit, and prevent the alternate current characteristics in the ordinary data reading from being adversely affected.

Abstract: A decoder circuit selectively controls the transfer gate group. The transfer gate group is stacked so as to form a tree structure having multiple stages of transfer gates and enable a monitoring bus line to be connected to any column in a memory cell array. This configuration enables the current in each memory cell to be monitored at an external pad via a single bus line, which reduces the area occupied by the bus lines, suppressing an increase in the chip size.

Abstract: A control circuit incorporated in a constant-voltage generating circuit receives a control signal. While the control signal is inactive, the control circuit sets the first and second nodes at the ground level and deactivates the current mirror circuit. When the control signal is activated, the control circuit releases the first and second nodes from the ground level and activates the current mirror circuit. Thus, no transient excessive charging of the bit line occurs immediately after the circuit is activated, and no soft-writing of data takes place.

Abstract: Memory cell arrays, in which memory cells are arranged in a matrix, are divided into a plurality of blocks. In a semiconductor memory device having the memory cell arrays, load circuits are connected to bus lines and the memory cell arrays. The number of load circuits is the same as that of the memory cell arrays. Thus, the load circuits function to supply the same amount of current to the bus lines, whatever block is activated in a writing operation. Therefore, writing characteristics of all the memory cell array blocks are the same.