Abstract: In a test mode, a first switch circuit is inactivated, and second and third switch circuits are activated. The oscillation frequency of a ring oscillator can be measured by measuring a delay value from the time a signal is input from a node inputting a test signal to the time it is output through the second switch circuit, inversion and delay circuit and the third switch circuit. Therefore, a semiconductor device capable of a simple measurement of the oscillation frequency can be provided.

Abstract: In a semiconductor memory device, a refresh circuit outputs a refresh command signal for executing refresh operation. The refresh circuit includes a command-signal activating circuit for activating the refresh command signal, and a determination circuit for determining whether the activated refresh command signal is to be output. The determination circuit determines that the activated refresh command signal is to be output when the semiconductor memory device is in a standby state. Thereby, the semiconductor memory device enables stable refresh operation to be executed.

Abstract: When address signal bits and/or data bits in a predetermined pattern are accessed a predetermined number of times successively, a test mode can be set. By using address signal bits and/or data bits as a test command for designating a test content, a test content is specified. A semiconductor memory device with an interface compatible with an interface of a normal static random access memory is provided.

Abstract: A dynamic-type memory A, a non-volatile memory B and a static-type memory C are enclosed in one package. Separated from a first terminal supplying a power-supply potential to the memories A and B, a second terminal supplying a power-supply potential to the memory C is provided. By stopping the supply of the power-supply potential to the first terminal at stand-by, stand-by current of a semiconductor memory device can be reduced. Therefore, the semiconductor memory device having an increased memory capacity while reducing a mounting area and consumption current at stand-by can be provided.

Abstract: Successive data read access with a final address specified is detected by a command mode detecting circuit to set a command mode entry status. In the command mode entry, a command of designating an internal state is made acceptable in accordance with a predetermined external signal. Consequently, a semiconductor memory device that enters a command mode, maintaining compatibility of pins and signal timings with a conventional static memory is provided.

Abstract: A semiconductor memory includes a first decoder selecting any of modes 1-n of a test mode B according to first to fourth data signals, and a second decoder selecting any of modes 1-n of the test mode B according to fifth to eighth data signals. When a predetermined mode m+1 is not set in a test mode A, the mode selected by both the first and second decoders is set. When the predetermined mode m+1 is set, the mode selected by the first decoder is set. Therefore, the test mode B can be set at the manufacturer side by connecting only four data input/output terminals to the tester.

Abstract: In a test mode, a first switch circuit is inactivated, and second and third switch circuits are activated. The oscillation frequency of a ring oscillator can be measured by measuring a delay value from the time a signal is input from a node inputting a test signal to the time it is output through the second switch circuit, inversion and delay circuit and the third switch circuit. Therefore, a semiconductor device capable of a simple measurement of the oscillation frequency can be provided.

Abstract: An output buffer includes first current driving units connected in parallel between a power-supply voltage and an output node; second current driving units connected in parallel between a ground voltage and an output node; a plurality of operation selection circuits setting the respective first and second current driving units to be in either activated or inactivated state in a non-volatile manner; first signal transmission circuits arranged respectively corresponding to the first current driving circuits and each transmitting the level of output data with a similar first propagation time period; and second signal transmission circuits arranged respectively corresponding to the second current driving units and each transmitting the level of the output data with a similar second propagation time period.

Abstract: Inter power supply surge voltage transmitting diode element is formed by a buried layer formed in a semiconductor substrate, a well region formed on the buried layer with its bottom portion being in contact with the buried layer, and impurity regions of mutually different conductivity types formed apart from each other at the surface of the well region. One of the impurity regions is electrically coupled to a first power supply line on which a surge voltage generates, and the other is electrically coupled to a second power supply line absorbing the surge voltage. The surge transmitting element includes a plurality of elements arranged parallel to each other between the first and second power supply lines. The second power supply line supplies the power supply voltage to an internal circuitry which consumes relatively small current.

Abstract: Inter power supply surge voltage transmitting diode element is formed by a buried layer formed in a semiconductor substrate, a well region formed on the buried layer with its bottom portion being in contact with the buried layer, and impurity regions of mutually different conductivity types formed apart from each other at the surface of the well region. One of the impurity regions is electrically coupled to a first power supply line on which a surge voltage generates, and the other is electrically coupled to a second power supply line absorbing the surge voltage. The surge transmitting element includes a plurality of elements arranged parallel to each other between the first and second power supply lines. The second power supply line supplies the power supply voltage to an internal circuitry which consumes relatively small current.

Abstract: In a semiconductor memory device having a plurality of data input/output pins, control pins (e.g. address pins and external control signal pins) are arranged parallel to each other on a chip. The plurality of data input/output pins are divided into a plurality of groups. Each group has a specific data input/output pin. The specific data input/output pin is lined up with the control pins. In a test mode, a signal is written into all memory cells by applying the signal to the specific data input/output pin. In addition, whether the signals read from all memory cells are correct or not is determined using the specific data input/output pin.

Abstract: A semiconductor integrated circuit according to the present invention comprises a synchronous SRAM, a signal generation circuit generating a chip selection signal, a clock signal etc. supplied to the synchronous SRAM, a voltage set circuit setting the voltage of a system power supply line and a controller controlling the signal generation circuit and the voltage set circuit. When setting the synchronous SRAM in a power down mode, the chip selection signal is set in a nonselective state and the power supply voltage of the system power supply line is stepped down to a standby potential. Thus, the synchronous SRAM enters a standby state having extremely low power consumption.

Abstract: An I/O protection circuit includes a P-channel MOS transistor connected between an input terminal and a power supply line, and an N-channel MOS transistor connected between the input terminal and a ground line. Gate electrodes of both the transistors are floated. The transistors may be replaced with gate diodes. Further, gate electrodes may be formed from the same layer as a gate electrode provided for field shielding.

Abstract: A memory cell includes driver transistors constituting a cross coupled type flipflop, access transistors driven in response to a signal potential on a word line, and bipolar transistors for connecting the memory cell to bit lines. For the bit lines, a read load circuit including diode coupled p channel MOS transistors and cross coupled p channel MOS transistors is provided, which supplies current when activated, and latches the bit line potentials after a prescribed time period. Stable data reading at high speed with low current consumption even under low power supply voltage is ensured, without causing data destruction.

Abstract: In a SRAM cell including a bipolar transistor and a cut transistor, the threshold Vtheff (Driver) of driver transistor and the threshold Vtheff (Cut) of cut transistor are set such that they satisfy the expressions,Vtheff(Driver).gtoreq.?{log(1 .mu.A)}-{log(Vcc/10R)}!.times.S(1)?{log(1 .mu.A)}-{log((Ie.times.(1/(hFE+1)))/10)}!.times.S.ltoreq.Vtheff(Cut).ltoreq.?{log(1 .mu.A)}-{log(Vcc/R)}!.times.S(2)Vtheff(Cut)-S.ltoreq.

Abstract: A memory cell data is read/written to a memory cell by utilizing the base current of a bipolar transistor having its emitter coupled to a bit line. When activated, a bit line precharge circuit precharges the bit line to a level of a built-in voltage between the emitter and the base of the memory cell bipolar transistor. When bit lines in a pair are lowered in potential from the H level to the L level, the base electrode node potential of the bipolar transistor is never changed to a negative potential by capacitance coupling, and conduction of an access transistor and destruction of memory cell data are prevented. A semiconductor memory device is implemented which does not cause data destruction and can stably operate at high speed even under a low power supply voltage.

Abstract: Bit lines (BL, /BL) are equally held low by a low-level precharge circuit (212) and an equalizing circuit (218) at time (t1) prior to a read operation. A read signal (/READ) and an equalization signal (EQ) go low at time (t2) when the read operation starts to provide "H" to word lines (WLU, WLL). If storage nodes (N1, N2) store "H" and "L" respectively, a bipolar transistor (BP2) is activated when the bit line (/BL) reaches a potential (+Vbe). Then, the potential of the bit line (/BL) does not rise to a power supply potential (VCC) but is held at the potential (+Vbe). Current flows to the bit line (/BL) through a reading load circuit (211) transiently (for a time period between times t2 and t3), but no current flows to the bit line (/BL) in a steady state (for a time period between times t3 and t4).

Abstract: In repairing a defective memory cell of a data memory placed in a data memory region, a repairing circuit which employs a repairing method causing some access penalty but having high repairing efficiency is located in a redundant row region and a redundant column region in the data memory region. On the other hand, in repairing a defective memory cell of a tag memory placed in a tag memory region, a repairing circuit which employs a repairing method having low repairing efficiency but causing little access penalty is located in a redundant column region in the tag memory region. Accordingly, optimal repair of a defective memory cell can be achieved according to respective functions of the tag memory and the data memory.

Abstract: A memory cell includes first and second driver transistors, first and second access transistors and first and second load elements, and in addition, first and second bipolar transistors. Accordingly, static noise margin is enlarged. The first bipolar transistor has its emitter formed in one of the source/drain regions of the first access transistor. The collector of the first bipolar transistor is the backgate terminal of the first access transistor. One of the source/drain regions of the first access transistor functions as the base of the first bipolar transistor. The same applies to the second bipolar transistor and the second access transistor. As the memory cell is structured in the above described manner, lower power supply potential can be used without the problem of latch up or increased area.

Abstract: A memory cell includes two bipolar transistors. An upper side word line is connected to the gates of one access transistor and one depletion type transistor in the memory cell. A lower side word line is connected to the gates of the other access transistor and the other depletion type transistor in the memory cell. In data write operation, the potential on the upper side word line is set to "H" level for a prescribed period and the potential on the lower side word line is thereafter set to "H" level for a prescribed period, regardless of the type of data. As a result, a circuit related to row decoding can be simplified since a circuit for determining the type of data is not necessary in the circuit related to row decoding.