Abstract: Leakage current in a standby mode of a level shifter capable of operating with low voltage is reduced. Provided is a level shifter circuit in which an n-channel silicon transistor and an oxide semiconductor transistor are provide in series between an output signal line and a low potential power supply line. The potential of a gate electrode of the oxide semiconductor transistor is raised to a potential higher than input signal voltage by capacitive coupling, so that on-state current of the oxide semiconductor transistor is increased.

Abstract: A semiconductor device that suppresses operation delay due to stop and restart of the supply of a power supply potential is provided. A potential corresponding to data held while power supply potential is continuously supplied is backed up in a node connected to a capacitor while the supply of the power supply potential is stopped. Then, by utilizing change in resistance of a channel in a transistor whose gate is the node, the data is restored with restart of the supply of the power supply potential. Note that by supplying a high potential to the node before the data back up, high-speed and accurate data back up is possible.

Abstract: A semiconductor device includes a photodiode, a first transistor, a second transistor, and a third transistor. The second transistor and the third transistor have a function of retaining a charge accumulated in a gate of the first transistor. In a period during which the second transistor and the third transistor are off, a voltage level of a voltage applied to a gate of the second transistor is set to be lower than a voltage level of a source of the second transistor and a voltage level of a drain of the second transistor, and a voltage level of a voltage applied to a gate of the third transistor is set to be lower than a voltage level of a source of the third transistor and a voltage level of a drain of the third transistor.

Abstract: A low-power semiconductor device is provided. A memory device applicable to a multi-context programmable logic device (PLD) includes at least memory cells the number of which is the same as the number of contexts. Output nodes of the memory cells are electrically connected to an output node of a configuration memory through different path transistors. A circuit including a transistor and a capacitor makes a gate potential of the path transistor higher than a high-level potential. This prevents a decrease in the potential of the output node of the configuration memory due to the threshold voltage of the path transistor without an increase in power consumption.

Abstract: A semiconductor device with a novel structure that can consume less power and have a reduced size of a circuit. In the semiconductor device, when configuration operation is started in a path transistor in a configuration memory, supply of an H-level potential to a signal pass node is stopped and then the potential of the signal pass node is set at L level, whereby configuration data is input to a memory potential retaining node, which is a gate of the path transistor. After the configuration operation is completed, the supply of the H-level potential to the signal pass node is resumed so that capacitive coupling occurs between the path transistor and the memory potential retaining node and increase the gate potential of the path transistor, so that a boosting effect is obtained. The above structure eliminates the need for a keeper circuit, reducing the power consumption and the circuit area.

Abstract: To provide a semiconductor device having a novel configuration, in which a malfunction and power consumption are reduced. A data holding circuit which includes a flipflop including first and second latch circuits and a shadow register including a nonvolatile memory portion; and a control signal generation circuit which generates a first control signal supplied to the first latch circuit and a second control signal supplied to the second latch circuit are included. The shadow register is a circuit which controls data saving or data restoring between the first and second latch circuits on the basis of a saving control signal or a restore control signal. The control signal generation circuit is a circuit which generates the first and second control signals at L level in a period during which data is saved or restored, on the basis of a clock signal, the saving control signal, and the restore control signal.

Abstract: A semiconductor device that can operate normally with lower power consumption is provided. The semiconductor device includes a pair of first circuits which each include a first transistor and a second transistor capable of controlling the supply of a first signal to a gate of the first transistor, and a second circuit which is capable of generating a second signal which is to be supplied to a gate of the second transistor and which has a larger amplitude than the first signal. One of a source and a drain of one of the first transistors included in the pair of first circuits is electrically connected to one of a source and a drain of the other of the first transistors. The first signals supplied to the gates of the first transistors in the pair of first circuits have potentials with different logic levels.

Abstract: Data of a register in a programmable logic element is retained. A volatile storage circuit and a nonvolatile storage circuit are provided in a register of a programmable logic element whose function can be changed in response to a plurality of context signals. The nonvolatile storage circuit includes nonvolatile storage portions for storing data in the register. The number of nonvolatile storage portions corresponds to the number of context signals. With such a structure, the function can be changed each time context signals are switched and data in the register that is changed when the function is changed can be backed up to the nonvolatile storage portion in each function. In addition, the function can be changed each time context signals are switched and the data in the register that is backed up when the function is changed can be recovered to the volatile storage circuit.

Abstract: An object is to achieve low-power consumption by reducing the off-state current of a transistor in a photosensor. A semiconductor device including a photosensor having a photodiode, a first transistor, and a second transistor; and a read control circuit including a read control transistor, in which the photodiode has a function of supplying charge based on incident light to a gate of the first transistor; the first transistor has a function of storing charge supplied to its gate and converting the charge stored into an output signal; the second transistor has a function of controlling reading of the output signal; the read control transistor functions as a resistor converting the output signal into a voltage signal; and semiconductor layers of the first transistor, the second transistor, and the read control transistor are formed using an oxide semiconductor.

Abstract: Adverse effects of noise are reduced. A photodetector circuit, a difference data generation circuit, and a data input selection circuit are included. The photodetector circuit has a function of generating an optical data signal. A first data signal and a second data signal is input to the difference data generation circuit and the difference data generation circuit has a function of generating difference data of data of the first data signal and data of the second data signal. The data input selection circuit has a function of determining that the data of optical data signal is regarded as data of the first data signal or data of the second data signal.

Abstract: A programmable logic device includes a plurality of programmable logic elements (PLE) whose electrical connection is controlled by first configuration data. Each of The PLEs includes an LUT in which a relationship between a logic level of an input signal and a logic level of an output signal is determined by second configuration data, an FF to which the output signal of the LUT is input, and an MUX. The MUX includes at least two switches each including first and second transistor. A signal including third configuration data is input to a gate of the second transistor through the first transistor. The output signal of the LUT or an output signal of the FF is input to one of a source and a drain of the second transistor.

Abstract: To provide a highly reliable and low-power-consumption semiconductor device functioning as a programmable logic device. A monitor circuit is provided to monitor a change in the potential of a configuration memory in which a transistor is turned off to hold charge and a potential corresponding to the charge is stored as configuration data. The reset of the configuration data is controlled in accordance with the potential change. With such a structure, the configuration memory can be reconfigured before the configuration data is lost, resulting in improved reliability of the semiconductor device. In addition, reconfiguration can be performed every time data is lost. Accordingly, power consumption can be reduced as compared with the structure where reconfiguration is performed periodically.

Abstract: In a CMOS image sensor in which a plurality of pixels is arranged in a matrix, a transistor in which a channel formation region includes an oxide semiconductor is used for each of a charge accumulation control transistor and a reset transistor which are in a pixel portion. After a reset operation of the signal charge accumulation portion is performed in all the pixels arranged in the matrix, a charge accumulation operation by the photodiode is performed in all the pixels, and a read operation of a signal from the pixel is performed per row. Accordingly, an image can be taken without a distortion.

Abstract: To provide a PLD having a reduced circuit area and an increased operation speed. In the circuit structure, a gate of a transistor provided between an input terminal and an output terminal of a programmable switch element is in an electrically floating state in a period when a signal is input to the programmable switch element. The structure enables the voltage of a gate to be increased by a boosting effect in response to a signal supplied from programmable logic elements, suppressing a reduction in amplitude voltage. This can reduce a circuit area by a region occupied by a booster circuit such as a pull-up circuit and increase operation speed.

Abstract: A semiconductor device includes a photodiode, a first transistor, a second transistor, and a third transistor. The second transistor and the third transistor have a function of retaining a charge accumulated in a gate of the first transistor. In a period during which the second transistor and the third transistor are off, a voltage level of a voltage applied to a gate of the second transistor is set to be lower than a voltage level of a source of the second transistor and a voltage level of a drain of the second transistor, and a voltage level of a voltage applied to a gate of the third transistor is set to be lower than a voltage level of a source of the third transistor and a voltage level of a drain of the third transistor.

Abstract: To provide a charge pump circuit to manufacture a low-power-consumption PLD. A semiconductor device includes a first circuit and a second circuit electrically connected to the first circuit. A charge pump circuit formed of a transistor including an oxide semiconductor and a boosting control circuit controlling the charge pump circuit are provided between the first circuit and the second circuit. The first circuit and the charge pump circuit operate at first power supply voltage, and the boosting control circuit and the second circuit operate at second power supply voltage. The first power supply voltage is lower than the second power supply voltage.

Abstract: A semiconductor device includes a photodiode, a first transistor, a second transistor, and a third transistor. The second transistor and the third transistor have a function of retaining a charge accumulated in a gate of the first transistor. In a period during which the second transistor and the third transistor are off, a voltage level of a voltage applied to a gate of the second transistor is set to be lower than a voltage level of a source of the second transistor and a voltage level of a drain of the second transistor, and a voltage level of a voltage applied to a gate of the third transistor is set to be lower than a voltage level of a source of the third transistor and a voltage level of a drain of the third transistor.

Abstract: In a CMOS image sensor in which a plurality of pixels is arranged in a matrix, a transistor in which a channel formation region includes an oxide semiconductor is used for each of a charge accumulation control transistor and a reset transistor which are in a pixel portion. After a reset operation of the signal charge accumulation portion is performed in all the pixels arranged in the matrix, a charge accumulation operation by the photodiode is performed in all the pixels, and a read operation of a signal from the pixel is performed per row. Accordingly, an image can be taken without a distortion.

Abstract: To provide a PLD having a reduced circuit area and an increased operation speed. In the circuit structure, a gate of a transistor provided between an input terminal and an output terminal of a programmable switch element is in an electrically floating state in a period when a signal is input to the programmable switch element. The structure enables the voltage of a gate to be increased by a boosting effect in response to a signal supplied from programmable logic elements, suppressing a reduction in amplitude voltage. This can reduce a circuit area by a region occupied by a booster circuit such as a pull-up circuit and increase operation speed.

Abstract: A display device includes a pixel area including pixels arranged in a matrix and having a horizontal resolution of 350 ppi or more and a color filter layer overlapping with the pixel area. The pixels each include a first transistor whose gate is electrically connected to a scan line and whose one of a source and a drain is electrically connected to a signal line; a second transistor whose gate is electrically connected to the other of the source and the drain of the first transistor and whose one of a source and a drain is electrically connected to a current-supplying line; and a light-emitting element electrically connected to the other of the source and the drain of the second transistor. The first and second transistors each have a channel formation region including a single crystal semiconductor.