Nippon Steel Corporation

Yoshikawa Rf Systems Co., Ltd.

Fuji Xerox Co., Ltd.

Oki Electric Industry Co., Ltd.

Kikuzo Sawada

Yoshikazu Sugawara

Takashi Kubo

Toshio Wada

Kenji Suzuki

Yasuo Sato

Tomoaki Yoshida

Hiroshi Mawatari

Nobuhiro Tomari

Kouzi Tanagawa

Naotaka Yasuda

Yuming Tang

The data carrier has a communication protocol storage unit storing a communication protocol for communicating with an external communication device, an RF analogue receiver receiving an interrogation signal from the external communication device as an RF signal, a contact communication end terminal unit performing contact communication with the external communication device, a communication command controller controlling a command used in an RF communication protocol performed via said RF analogue receiver or a contact-type serial communication protocol performed via said contact communication end terminal unit, and a connection selector selectively connecting one of said RF analogue receiver and said contact communication end terminal unit with said communication command controller.

Data carrier and data carrier system

A region to store authentication commands to perform authentication between a data carrier and a reader/writer device is divided into at least three areas, and as for the three areas, a first authentication command is stored in a first area, a second authentication command is stored in a second area, and a third authentication command is stored in a third area, and security levels can be selected depending on a command of an inquiry signal () transmitted from a reader/writer device (), and thereby selection of the security level suitable for circumstances can be realized by a simple constitution.

Both RF communication and contact serial communication can be performed with the use of: communication protocol storage unit for storing a communication protocol for performing communication with an external communication apparatus; a coil terminal section provided with two coil terminals for performing communication with the external communication apparatus with an RF signal; a contact communication terminal section provided with a first communication terminal, a second communication terminal, a power supply voltage terminal and a ground terminal as contact communication terminals for performing contact communication with the external communication apparatus; and connection control unit for causing the power supply voltage terminal and a power supply of an internal switch circuit to be in contact or non-contact with each other depending on the level of voltage applied to the first and second communication terminals.

The semiconductor booster circuit includes a plurality of stages, each of which has a MOS transistor and two capacitors. The MOS transistor, having a drain, a source and a gate, is formed in a well of a substrate portion. One capacitor has a terminal connected to the drain of the MOS transistor, while the other capacitor has a terminal connected to the gate of the MOS transistor. A first clock signal generating means generate a first clock signal via another terminal of one capacitor. A second clock signal generating mean s generate a second clock signal, with a larger amplitude than a power supply voltage, via another terminal of another capacitor. The plurality of stages are cascaded together, and in each of the stages the source of the MOS transistor is electrically connected to the well in which the transistor is formed, while the wells are electrically insulated from each other.

Semiconductor booster circuit having cascaded MOS transistors

A semiconductor booster circuit includes: a plurality of stages, each having a first MOS transistor and a first capacitor having one terminal connected to a drain terminal of the first MOS transistor, the stages being connected in series by connecting the first MOS transistors of the stages in cascade; and at least one of a first arrangement wherein a source terminal of the first MOS transistor of each of the stages is electrically connected to its substrate, and the substrates of the first MOS transistors in the plurality of stages are electrically insulated from one another, and a second arrangement wherein one terminal of a second capacitor is connected to a gate terminal of the first MOS transistor of each of the stages, and a first clock signal generating unit for inputting a first clock signal to the other terminal of the first capacitor in each stage and a second clock signal generating unit for inputting a second clock signal having a larger amplitude than a power supply voltage (Vdd) to the other terminal of the second capacitor, in each stage are provided.

An electrically alterable nonvolatile semiconductor memory device has a first memory array including a plurality of first memory cells and a second memory array including at least one second memory cell, wherein contents of the first memory array and contents of the second memory array are capable of being altered independently of each other and variation of a specific quality of each second memory cell due to altering of the contents of the second memory cell is examined, in order to estimate the life of the first memory array.

Electrically alterable nonvolatile semiconductor memory

The promotion of reduction of the power source voltage for use in a nonvolatile semiconductor memory is attained by using a method wherein memory cells each of which includes a control gate having a floating gate above a channel region, and a source constituted by an N-type impurity diffusion layer enclosed with a high impurity concentrated P-type diffusion layer containing impurities the impurity concentration of which is higher than that of a P-type well are formed in double wells made up of an N-type well and the P-type well which are formed in a P-type silicon substrate, the electric potentials at the N-type well and the P-type well are controlled independently to each other to write data to the memory cell by utilizing the tunnel phenomenon, the electrical potential at the P-type well is made negative, and under this condition, a relatively low positive voltage and a high voltage are respectively applied to the control gate and the source and the hot electrons generated in the vicinity of the source are injected into the floating gate through the channel region by utilizing the tunnel phenomenon to erase the information stored in the memory cell.

Nonvolatile semiconductor memory and method of rewriting data thereto

An electrically alterable non-volatile semiconductor memory device includes a plurality of electrically alterable memory cells arranged in columns and rows, a decoder circuit which selects at least one of the plurality of memory cells and does not select others, a writing circuit for writing a selected data in the selected memory cell through the decoder circuit, a reading circuit for reading a data stored in the selected memory cell through the decoder circuit, a comparing circuit for holding the data stored in the selected memory cell and data to be written in the memory cell and comparing both the data with each other, a judging circuit for judging whether the stored data in the selected memory cell is required to be altered or not on the basis of the comparison result of the comparing circuit, and an alteration control circuit for performing altering of the data of the memory cell when stored data is required to be altered on the basis of the judgment result of the judging circuit.

Non-volatile semiconductor memory device

A power supply circuit selectively provides various voltage signals to memory devices, such as EPROM or EEPROM for example. The power supply circuit receives voltage signals at input terminals and selectively outputs a voltage signal, in accordance with the requirement for reading, writing and erasing operations, while preventing leakage current between voltage signals. Among other things, the power supply circuit provides a relatively low impedance and does not require high voltage levels for performing the above memory operations. The selection of voltage signals at an output terminal is effected by control means for controlling conductivity and non-conductivity of MOS transistors based on a control signal supplied from a control signal input terminal.

Voltage selecting device for receiving a plurality of inputs and

A bootstrap circuit particularly suitable for low voltage applications and use with semiconductor memories is disclosed.

Bootstrap circuit

An electrically alterable non-volatile semiconductor memory. The memory cells are formed in a matrix of columns and rows. A row decoder and column decoder are provided to select one of the row lines and column lines. Mode selection means are provided for selecting a writing mode, a first erasing mode for erasing a row of memory cells, a second erasing mode for erasing a selected memory cell on a bit basis, and a reading mode for reading the contents of each memory cell. The individual erasing modes reduce the overall power consumption of the device, while permitting block erasing as well as individual cell erasing.

Non-volatile semiconductor memory device and a method of using the same

The electrically rewritable nonvolatile semiconductor memory device includes a plurality of memory cells arranged in rows and columns, a decoder circuit for selecting at least one of the plurality of memory cells, a writing circuit for writing data in the selected memory cell through the decoder circuit, a reading circuit for reading the data from the selected memory cell, a detecting circuit for detecting a change of the threshold voltage of each of the non-selected memory cells, which change is caused by a voltage applied to the non-selected memory cell when writing the data in the selected memory cell, and a restoring circuit for restoring the threshold voltage of the non-selected memory cell a value equal to or near to its original value on the basis of the result of the above detection.

Non-volatile semiconductor memory device having disturb verify function

A non-volatile semiconductor memory device capable of electrical programming including a plurality of memory cells, means for selecting at least one memory cell from the plurality of memory cells, mode setting means for setting one of a first read mode in which data written in the selected memory cell is read and a second read mode for detecting a change of the threshold voltage level of the selected memory cell, first comparing means for comparing a voltage signal read from the selected memory cell with at least a predetermined single first reference voltage level when the first read mode is set, first output means for producing a signal indicative of data written in the selected memory cell on the basis of the comparison in the first comparing means, second comparing means for comparing the cell voltage signal with at least a predetermined single second reference voltage level different from the first reference voltage level when the second read mode is set, and second output means for producing a signal indicative of a change of the threshold voltage of the selected memory cell on the basis of the comparison in the second comparing means.

Non-volatile semiconductor memory device detachable deterioration of

A method of writing or reading at least three different data in each memory cell, in a non-volatile semiconductor memory device having a plurality of memory cells, each memory cell having floating gate for setting a given threshold voltage in the memory cell. In addition, a non-volatile semiconductor memory device capable of checking if the data stored in the selected memory cell is correct by using one of at least two binary bits of the data as a parity bit, and a method of writing or reading data in or from that memory device.

Non-volatile semiconductor memory device having memory cells, each for

An electrically erasable non-volatile semiconductor memory device comprising a plurality of row lines and column lines, a plurality of memory cells connected in a matrix to the plurality of row lines and column lines, a selection circuit for selecting a desired one of the plurality of memory cells, and write-control circuit for writing data into the plurality of memory cells. The write-control circuit is adapted to preset at least four voltage signals having different voltage values, and to select one of four voltage signals according to a data signal externally applied thereto and applying the selected voltage signal to the selected memory cell. Also included is read-control circuit for reading out data written into the selected memory cell and converting the data read-out from the selected memory cell into a data signal corresponding to one of the four voltage signals.

Growing community of inventors

Tokyo, Japan

Kikuzo Sawada