Renesas Technology Corp.

Mitsubishi Denki Kabushiki Kaisha

Zengcheng Tian

Tadaaki Yamauchi

Junko Matsumoto

Takeo Okamoto

Makoto Suwa

Hideki Yonetani

Tsutomu Nagasawa

Tetsuichiro Ichiguchi

Kozo Ishida

Shinichi Jinbo

Shin Sekiya

Koji Kimura

Masaki Nishimoto

Shigekazu Aoki

Akihiro Shirai

Masayuki Kasamoto

Yukihiro Tsukamoto

Kazuhisa Uetsuki

Naotaka Okada

Masakatsu Murakami

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.

Semiconductor device having internal voltage generated stably

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.

Semiconductor circuit device adaptable to plurality of types of packages

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.

Semiconductor memory device requiring refresh operation

A row address decoder of a semiconductor memory device generates internal row address signals RAD< and /RAD< > by switching most significant bit and least significant bit of row address signals RA< > and /RA< > that correspond to address signals A to A , respectively. In a twin cell mode, the least significant bits RAD< > and /RAD< > of the internal row address signals corresponding to the most significant bits RA< > and /RA< > 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.

Semiconductor memory device switchable to twin memory cell configuration

A clock buffer of a DRAM includes: a first NAND gate which is driven by a first internal power supply voltage (2.5 V) and which determines the level of an input clock signal if the DRAM is used for a TTL-system interface (MLV&equals;2.5 V); and a second NAND gate which is driven by a second internal power supply voltage (1.8 V) and which determines the level of the input clock signal if the DRAM is used for a 1.8 V-system interface (MLV&equals;0 V). Accordingly, in each of the first and second NAND gates, sizes of four MOS transistors can be set at optimum values, respectively.

Semiconductor device used in two systems having different power supply voltages

A semiconductor memory device includes banks, predecoders, a latch circuit, a counter, a fuse and buffers. The bank includes a plurality of memory cells arranged in rows and columns, and others. The predecoders are disposed in a central portion of the semiconductor memory device. The predecoder produces a predecode signal for selecting each of the banks based on a bank address received from the buffer, and outputs the predecode signal to the banks. The predecoder produces the predecode signal for selecting each of the banks based on the bank address, and outputs the predecode signal to the banks. Consequently, interconnections in the central portion can be reduced in number.

Semiconductor memory device allowing high density structure or high performance

A level conversion circuit is provided, at an output, with an initialization circuit for setting the output signal of the level conversion circuit for generating a power cut enable signal controlling a deep power down mode to a predetermined inactive state upon power up. The initialization circuit is constituted by, for example, a capacitive element connected to the output node of the level conversion circuit to pull up the voltage of the output node upon power up, and a latch circuit latching the voltage level of the output node. When power is on, the power cut enable signal is forcibly inactivated by the initialization circuit to generate a periphery power supply voltage. The internal node of the level conversion circuit is initialized according to the output signal of a control circuit receiving the periphery power supply voltage as an operating power supply voltage. In semiconductor memory device having a deep power down mode, an internal voltage is generated reliably and properly upon power up of an internal voltage.

Semiconductor device

Pad lines are placed on the peripheral region of a chip along EAST band and WEST band (E/W band). In order to allow the chip with pads arranged on the peripheral region to be adaptable to a TSOP, VDD and VSS pads are arranged on the edge region on NORTH band and SOUTH band (N/S band) near the center of the N/S band. Moreover, in consideration of frame design for the TSOP, some pads on the ends of the pad lines among the pads included in the pad lines are arranged in reverse order relative to the order of pins. Further, VDDQ and VSSQ pads are arranged in the same order as that of pins for a package which requires no consideration of frame design. On the other hand, for use in a BGA package, VDD and VSS pads are arranged in pairs at respective ends of the pad lines. A semiconductor memory device with this pad arrangement is accordingly adaptable to various types of packages.

Semiconductor memory device adaptable to various types of packages

When a special operation mode is instructed, a test oscillation circuit operating at a cycle shorter than a refresh oscillation circuit specifying the cycle of self refresh is activated according to an external row address strobe signal. The internal row address strobe signal is provided to row related control circuitry via a selector. An internal row address strobe signal can be rendered active at a cycle shorter than the cycle of the external row address strobe signal, to carry out row selection. A row is selected at a cycle shorter than the transition cycle of an external signal.

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Zengcheng Tian