Fujitsu Corporation

Fujitsu Vlsi Limited

Akihiro Iwase

Teruo Seki

Hajime Sato

Yoshiharu Kato

Syuichi Saito

Akira Sugiura

Isaya Sobue

Tohru Yasuda

Masaharu Kagohashi

Chiaki Furukawa

Seiji Yamamoto

Hirosuke Koumyoji

Mikio Ishikawa

Tomio Nakano

Shinji Nagai

Tadashi Ozawa

Shinzi Nagai

Sinzi Nagai

A voltage generator circuit which is capable of preventing the generation of a through current in a transition to a power-down mode to reduce current consumption. The voltage generator circuit includes a voltage generator activated by a reference voltage to generate an output voltage. A reference voltage clamp circuit is coupled to the voltage generator for clamping the reference voltage to a first voltage in response to a power-down signal to deactivate the voltage generator. An output voltage clamp circuit is coupled to the voltage generator for clamping the output voltage to a second voltage. A control circuit is coupled to the output voltage clamp circuit for enabling the output voltage clamp circuit after the voltage generator is deactivated in response to the power-down signal.

Voltage generator circuit and method for controlling thereof

A multi-bus semiconductor device and a method of its probing test perform the DC test for individual pads of a device while dealing with an adequate number of devices for simultaneous measurement based on the scheme of input/output pad number compressive test. The semiconductor device includes switch elements SW-SWconnected between input/output pads P-Pand a testing line Lso that pads in an arbitrary combination, among the off-probe pads P-Pthat are not made in contact with the tester probe Pr, are selected for testing in correspondence to the combination of switch elements that are turned on. The input/output buffers of the pads under test are deactivated to block their internal current paths. The corresponding switch elements are turned on to connect the off-probe pads under test to the probe pad Pthat is made in contact with the tester probe Pr, and the leak current of the probes is measured with the tester TS.

Semiconductor device and test method for the same

A multi-bus semiconductor device and a method of its probing test perform the DC test for individual pads of a device while dealing with an adequate number of devices for simultaneous measurement based on the scheme of input/output pad number compressive test. The semiconductor device includes switch elements SW-SWconnected between input/output pads P-Pand a testing line Lso that pads in an arbitrary combination, among the off-probe pads P-Pthat are not made in contact with the tester probe Prare selected for testing in correspondence to the combination of switch elements that are turned on. The input/output buffers of the pads under test are deactivated to block their internal current paths. The corresponding switch elements are turned on to connect the off-probe pads under test to the probe pad Pthat is made in contact with the tester probe Prand the leak current of the probes is measured with the tester TS.

A semiconductor device has a normal operation mode and a test mode. A decision circuit determines whether the device has entered the test mode. A control circuit changes information related to the normal operation mode when a test mode has been entered. If the test mode is accidentally entered, then because the information related to normal operation has been changed, a user can readily determine that the device has entered the test mode.

Semiconductor device having test mode entry circuit

A semiconductor device with an expanded range of a recommended condition for an input voltage is disclosed. In embodiment, the semiconductor device having input protection on an input terminal thereto, includes: a semiconductor region having a first conducting type, first and second diffusion regions defined in the semiconductor region and respectively having a second conducting type, and a transistor formed by using the semiconductor region as a base, the first diffusion region as a collector, and the second diffusion region as an emitter. The first diffusion region is connected to one of a high-potential power supply and a low-potential power supply, the second diffusion region is connected to the input terminal, and the semiconductor region is connected to another power supply having a voltage high enough to reverse bias the junction between the semiconductor region and the first diffusion region.

Semiconductor device having input protective function

A semiconductor memory includes a power down pulse generating circuit having an output delay time which is dependent on the type of change or transition in an input signal. The pulse generating circuit generates a power down signal at different times depending on whether the input signal changes from a first level to a second level or from the second level to the first level to prevent the power down signal from being output twice when an input clock signal has a pulse width shorter than a normal pulse width thereof. The power down pulse generating circuit generates the power down signal in response to a signal from address transition detection circuitry, and causes data read/write circuitry and bit line pulse generating circuitry to become inactive to reduce power consumption. The bit line pulse generating circuitry generates reset signals which may be used to reset or precharge the bit lines at different timings to reduce peak current in the semiconductor memory.

Semiconductor memory including bit line reset circuitry and a pulse

A semiconductor memory device includes a sense amplifier and a load circuit which are connected to a pair of data buses through which cell data is read. The sense amplifier produces an output data signal in accordance with voltage potentials of transfer signals on the data buses. During data reading operation of the memory device, the sense amplifier is enabled and the transfer signals on the data buses have a different voltage potential level from each other. The load circuit sets the data buses at a predetermined reset voltage potential in a stand by state of the data reading operation. The reset voltage potential is intermediate of the voltage potential levels of the data buses when the sense amplifier is enabled.

Data outputting circuit for semiconductor memory device

Disclosed is a semiconductor memory device which operates based on voltages from a high voltage power source and a low voltage power source. A plurality of memory cells are formed in a memory cell array. Plural pairs of bit lines are connected to the memory cells to transfer data signals read from the memory cells. A sense amplifier, which has a pair of input terminals, amplifies the data signal. A level shifter is selectively connected to plural pairs of bit lines to shift the level of the data signal of a selected pair of bit lines to a level near the operation point of the sense amplifier, and supplies a resultant data signal to the sense amplifier. The level shifter includes a first transistor for receiving the data signal, and a plurality of second transistors connected between the first transistor and the low voltage power source. The first transistor has a first terminal to be supplied with the data signal, a second terminal and a control electrode for receiving a control signal for transferring the data signal to the sense amplifier. The second transistors are connected between the second terminal of the first transistor and the low voltage power source. The output of the second terminal of the first transistor is input to the input terminals of the sense amplifier.

Semiconductor memory device with improved speed for reading data

A load generator is disclosed, which controls the voltage swing of the complementary logic signals generated in a semiconductor memory device. The load generator includes a first load circuit for controlling the potential levels of the signals appearing on a pair of complementary input signal lines. The first load circuit includes a first and second voltage dividers connected to the complementary input signal lines. Each of the first and second voltage dividers include a first voltage dividing transistor and a first voltage dividing resistive element connected in series between the semiconductor's low and high potential power supplies. The two first voltage dividing transistors are connected to each other in such a manner that a voltage, divided by one of the two transistors, is applied to the gate of the other transistor. The load generator further includes a second load circuit for controlling the potential levels of the signals appearing on a pair of complementary output signal lines. The second load circuit includes a third and fourth voltage dividing circuits associated with the first and second voltage dividing circuits and connected to the complementary output signal lines, respectively. Each of the third and fourth voltage dividing circuits includes a second voltage dividing transistor and a second voltage dividing resistive element, connected in series between the low and high potential power supplies.

Load generator used in semiconductor memory device

A delay circuit having two or more first switching transistors connected in series between an output terminal and a power source line, and two or more second switching transistors connected in series between the output terminal and another power source line, the first and the second switching transistors operating in a complementary manner in response to an input signal, one or more nodes of each switching transistor being connected by one or more current paths each connecting at least one capacitor, whereby an input signal is transmitted to the output terminal at a specified interval defined by the capacitance of the capacitor.

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Kasugai, Japan

Akihiro Iwase