Abstract: Provided is a semiconductor device capable of holding data for a long period. The semiconductor device includes first to third transistors, a capacitor, and a circuit. The third transistor includes a first gate and a second gate. A gate of the first transistor is electrically connected to a first terminal of the capacitor. A first terminal of the first transistor is electrically connected to the second gate. A second terminal of the first transistor is electrically connected to the circuit. A gate of second transistor is electrically connected to a first terminal of the second transistor. A first terminal of the second transistor is electrically connected to the second gate. A second terminal of the second transistor is electrically connected to a first terminal of the capacitor. The circuit is configured to generate a negative potential. A channel formation region of the first transistor preferably includes an oxide semiconductor.

Abstract: Provided is a structure which is capable of central control of an electric device and a sensor device and a structure which can reduce power consumption of an electric device and a sensor device. A central control system includes at least a central control device, an output unit, and an electric device or a sensor device. The central control device performs arithmetic processing on information transmitted from the electric device or the sensor device and makes the output unit output information obtained by the arithmetic processing. It is possible to know the state of the electric device or the sensor device even apart from the electric device or the sensor device. The electric device or the sensor device includes a transistor which includes an activation layer using a semiconductor with the band gap wider than that of single crystal silicon.

Abstract: A highly reliable semiconductor device that is suitable for high-speed operation is provided. A semiconductor device includes a first circuit, a second circuit, and a third circuit. The first circuit has an arithmetic processing function. The second circuit includes a memory circuit. The memory circuit includes a transistor which includes a first conductor, a second conductor, a first insulator, a second insulator, and a semiconductor. The first conductor includes a region overlapping the semiconductor with the first insulator positioned between the first conductor and the semiconductor. The second conductor includes a region overlapping the semiconductor with the second insulator positioned between the second conductor and the semiconductor. The first conductor is capable of selecting on or off of the transistor. The third circuit is electrically connected to the second conductor, and is capable of changing the potential of the second conductor in synchronization with an operation of the transistor.

Abstract: Provided is a semiconductor device which has low power consumption and can operate at high speed. The semiconductor device includes a memory element including a first transistor including crystalline silicon in a channel formation region, a capacitor for storing data of the memory element, and a second transistor which is a switching element for controlling supply, storage, and release of charge in the capacitor. The second transistor is provided over an insulating film covering the first transistor. The first and second transistors have a source electrode or a drain electrode in common.

Abstract: A semiconductor device is provided in which the power consumption can be reduced by reducing the driving voltage and the on-state current can be increased in a period in which a transistor having an extremely low off-state current is brought into an electrically floating state. The semiconductor device comprises a memory cell, a first circuit, and a second circuit. The memory cell includes a first transistor. The first transistor includes a first semiconductor layer, a first gate electrode, and a first back gate electrode. The first gate electrode is connected to a word line. The first back gate electrode is connected to a back gate line. The first circuit supplies a signal for controlling the conduction state of the first transistor to the word line. The second circuit supplies a voltage for controlling the threshold voltage of the first transistor to the back gate line.

Abstract: A semiconductor device which can write and read multilevel data is provided. A node connecting a source or a drain of an OS transistor and a gate of an OS transistor can hold the distribution of a plurality of potentials. A circuit configuration is employed in which the potential of the node is changed by capacitive coupling to control a conduction state of the OS transistor whose gate is connected thereto so that the potential of a gate of a Si transistor is changed. The potential of the gate of the Si transistor is changed positively in accordance with the potential change by capacitive coupling and is changed negatively in accordance with another transistor. In accordance with a change in value of current flowing through the Si transistor is detected, written data is read.

Abstract: [Problem] To provide a semiconductor device suitable for miniaturization. To provide a highly reliable semiconductor device. To provide a semiconductor device with improved operating speed. [Solving Means] A semiconductor device including a memory cell including first to cth (c is a natural number of 2 or more) sub memory cells, wherein: the jth sub memory cell includes a first transistor, a second transistor, and a capacitor; a first semiconductor layer included in the first transistor and a second semiconductor layer included in the second transistor include an oxide semiconductor; one of terminals of the capacitor is electrically connected to a gate electrode included in the second transistor; the gate electrode included in the second transistor is electrically connected to one of a source electrode and a drain electrode which are included in the first transistor; and when j?2, the jth sub memory cell is arranged over the j?1th sub memory cell.

Abstract: Provided is a semiconductor device that can directly compare two negative potentials. The semiconductor device includes a first to a third transistor and a load and is configured to compare a first negative potential and a second negative potential. The first negative potential and the second negative potential are input to a gate of the first transistor and a gate of the second transistor, respectively. Each drain of the first transistor and the second transistor is electrically connected to the load. The third transistor serves as a current source. The first transistor and the second transistor each include a backgate. A positive potential is input to the backgates.

Abstract: A novel semiconductor device that can write and read multilevel data is provided. A memory cell includes a bit line, a power supply line, first and second nodes, first to fourth transistors, and first and second capacitors. One of two divided multilevel data is written to the first node through the first transistor. The other of the divided multilevel data is written to the second node through the second transistor. A gate of the third transistor is connected to the first node, and a gate of the fourth transistor is connected to the second node. The third and fourth transistors control electrical continuity between the bit line and the power supply line. Each of the first and second transistors preferably includes an oxide semiconductor in a semiconductor layer.

Abstract: A semiconductor device capable of stably holding data for a long time is provided. A transistor including a back gate is used as a writing transistor of a memory element. In the case where the transistor is an n-channel transistor, a negative potential is supplied to a back gate in holding memory. The supply of the negative potential is stopped while the negative potential is held in the back gate. In the case where an increase in the potential of the back gate is detected, the negative potential is supplied to the back gate.

Abstract: Provided is a semiconductor device capable of holding data for a long period. The semiconductor device includes first to third transistors, a capacitor, and a circuit. The third transistor includes a first gate and a second gate. A gate of the first transistor is electrically connected to a first terminal of the capacitor. A first terminal of the first transistor is electrically connected to the second gate. A second terminal of the first transistor is electrically connected to the circuit. A gate of second transistor is electrically connected to a first terminal of the second transistor. A first terminal of the second transistor is electrically connected to the second gate. A second terminal of the second transistor is electrically connected to a first terminal of the capacitor. The circuit is configured to generate a negative potential. A channel formation region of the first transistor preferably includes an oxide semiconductor.

Abstract: A semiconductor device capable of holding data for a long time is provided. The semiconductor device includes a first transistor, a second transistor, and a circuit. The first transistor includes a first gate and a second gate. The first transistor includes a first semiconductor in a channel formation region. The first gate and the second gate overlap with each other in a region with the first semiconductor provided therebetween. The second transistor includes a second semiconductor in a channel formation region. A first terminal of the second transistor is electrically connected to a gate of the second transistor and the second gate. A second terminal of the second transistor is electrically connected to the circuit. The circuit has a function of generating a negative potential. The second semiconductor has a wider bandgap than the first semiconductor.

Abstract: The semiconductor device includes a bit line, a transistor, a retention node, and a capacitor. The transistor has a function of charging or discharging the retention node. The capacitor has a function of retaining a potential of the retention node. A voltage greater than the sum of a writing voltage and a threshold voltage is applied to a gate of the transistor. When the transistor is turned on, a first potential is supplied to the bit line with a reference potential in a floating state. A voltage less than the sum of the writing voltage and the threshold voltage is applied to the gate of the transistor. When the transistor is turned on, a second potential is supplied to the bit line with a reference potential in a floating state. With use of the first and second potentials, the threshold voltage of the transistor is calculated without being influenced by parasitic capacitance and variations in the storage capacitance of the capacitor.

Abstract: Provided is a semiconductor device which has low power consumption and can operate at high speed. The semiconductor device includes a memory element including a first transistor including crystalline silicon in a channel formation region, a capacitor for storing data of the memory element, and a second transistor which is a switching element for controlling supply, storage, and release of charge in the capacitor. The second transistor is provided over an insulating film covering the first transistor. The first and second transistors have a source electrode or a drain electrode in common.

Abstract: A semiconductor device with a transistor having favorable electrical characteristics is provided. The semiconductor device has a memory circuit and a circuit that are over the same substrate. The memory circuit includes a capacitor, a first transistor, and a second transistor. A gate of the first transistor is electrically connected to the capacitor and one of a source and a drain of the second transistor. The circuit includes a third transistor and a fourth transistor that are electrically connected to each other in series. The first transistor and the third transistor each include an active layer including silicon, and the second transistor and the fourth transistor each include an active layer including an oxide semiconductor.

Abstract: [Problem] To provide a semiconductor device suitable for miniaturization. To provide a highly reliable semiconductor device. To provide a semiconductor device with improved operating speed. [Solving Means] A semiconductor device including a memory cell including first to cth (c is a natural number of 2 or more) sub memory cells, wherein: the jth sub memory cell includes a first transistor, a second transistor, and a capacitor; a first semiconductor layer included in the first transistor and a second semiconductor layer included in the second transistor include an oxide semiconductor; one of terminals of the capacitor is electrically connected to a gate electrode included in the second transistor; the gate electrode included in the second transistor is electrically connected to one of a source electrode and a drain electrode which are included in the first transistor; and when j?2, the jth sub memory cell is arranged over the j?1th sub memory cell.

Abstract: A microcontroller which operates in a low power consumption mode is provided. A microcontroller includes a CPU, a memory, and a peripheral circuit such as a timer circuit. A register in the peripheral circuit is provided in an interface with a bus line. A power gate for controlling supply control is provided. The microcontroller can operate not only in a normal operation mode where all circuits are active, but also in a low power consumption mode where some of the circuits are active. A volatile memory and nonvolatile memory are provided in a register, such as a register of the CPU. Data in the volatile memory is backed up in the nonvolatile memory before the power supply is stopped. In the case where the operation mode returns to the normal mode, when power supply is started again, data in the nonvolatile memory is written back into the volatile memory.

Abstract: Provided is a semiconductor device which can achieve a reduction in its area, reduction in power consumption, and operation at a high speed. A semiconductor device 10 has a structure in which a circuit 31 including a memory circuit and a circuit 32 including an amplifier circuit are stacked. With this structure, the memory circuit and the amplifier circuit can be mounted on the semiconductor device 10 while the increase in the area of the semiconductor device 10 is suppressed. Thus, the area of the semiconductor device 10 can be reduced. Further, the circuits are formed using OS transistors, so that the memory circuit and the amplifier circuit which have low off-state current and which can operate at a high speed can be formed. Therefore, a reduction in power consumption and improvement in operation speed of the semiconductor device 10 can be achieved.

Abstract: A semiconductor device which can write and read multilevel data is provided. Anode connecting a source or a drain of an OS transistor and a gate of an OS transistor can hold the distribution of a plurality of potentials. A circuit configuration is employed in which the potential of the node is changed by capacitive coupling to control a conduction state of the OS transistor whose gate is connected thereto so that the potential of a gate of a Si transistor is changed. The potential of the gate of the Si transistor is changed positively in accordance with the potential change by capacitive coupling and is changed negatively in accordance with another transistor. In accordance with a change in value of current flowing through the Si transistor is detected, written data is read.

Abstract: The semiconductor device includes a bit line, a transistor, a retention node, and a capacitor. The transistor has a function of charging or discharging the retention node. The capacitor has a function of retaining a potential of the retention node. A voltage greater than the sum of a writing voltage and a threshold voltage is applied to a gate of the transistor. When the transistor is turned on, a first potential is supplied to the bit line with a reference potential in a floating state. A voltage less than the sum of the writing voltage and the threshold voltage is applied to the gate of the transistor. When the transistor is turned on, a second potential is supplied to the bit line with a reference potential in a floating state. With use of the first and second potentials, the threshold voltage of the transistor is calculated without being influenced by parasitic capacitance and variations in the storage capacitance of the capacitor.