Abstract: The circuit includes a first wiring for supplying a power supply potential to a signal processing circuit, a transistor for controlling electrical connection between the first wiring and a second wiring for supplying the a power supply potential, and a transistor for determining whether or not the first wiring is grounded. At least one of the two transistors is a transistor whose channel is formed in the oxide semiconductor layer. This makes it possible to reduce power consumption due to cutoff current of at least one of the two transistors.

Abstract: A dynamic logic circuit in which the number of elements is reduced, the layout area is reduced, the power loss is reduced, and the power consumption is reduced is provided. A semiconductor device including a dynamic logic circuit includes a first transistor in which a channel is formed in silicon and a second transistor in which a channel is formed in an oxide semiconductor. Here, a structure in which the second transistor is provided over the first transistor can be employed. A structure in which an insulating film is provided over the first transistor, and the second transistor is provided over the insulating film can be employed. A structure in which a top surface of the insulating film is planarized can be employed. A structure in which the second transistor has a region overlapping with the first transistor can be employed.

Abstract: Noise generated on a word line is reduced without increasing a load on the word line. A semiconductor device is provided in which a plurality of storage elements each including at least one switching element are provided in matrix; each of the plurality of storage elements is electrically connected to a word line and a bit line; the word line is connected to a gate (or a source and a drain) of a transistor in which minority carriers do not exist substantially; and capacitance of the transistor in which minority carriers do not exist substantially can be controlled by controlling a potential of a source and a drain (or a gate) the transistor in which minority carriers do not exist substantially. The transistor in which minority carriers do not exist substantially may include a wide band gap semiconductor.

Abstract: The circuit includes a first wiring for supplying a power supply potential to a signal processing circuit, a transistor for controlling electrical connection between the first wiring and a second wiring for supplying the a power supply potential, and a transistor for determining whether or not the first wiring is grounded. At least one of the two transistors is a transistor whose channel is formed in the oxide semiconductor layer. This makes it possible to reduce power consumption due to cutoff current of at least one of the two transistors.

Abstract: An object is to provide a programmable logic device configured to keep a connection state of logic circuits even while power supply voltage is stopped. The programmable logic device includes arithmetic circuits each of whose logic state can be changed; a configuration changing circuit changing the logic states of the arithmetic circuits; a power supply control circuit controlling supply of power supply voltage to the arithmetic circuits; a state memory circuit storing data on the logic states and data on states of the power supply voltage of the arithmetic circuits; and an arithmetic state control circuit controlling the configuration changing circuit and the power supply control circuit in accordance with the data stored in the state memory circuit. A transistor in which a channel formation region is formed in an oxide semiconductor layer is provided between the configuration changing circuit and each of the arithmetic circuits.

Abstract: A novel semiconductor device and a driving method thereof are provided. In the semiconductor device, a (volatile) node which holds data that is rewritten by arithmetic processing as appropriate and a node in which the data is stored are electrically connected through a source and a drain of a transistor whose channel is formed in an oxide semiconductor layer. The off-state current value of the transistor is extremely low. Therefore, electric charge scarcely leaks through the transistor from the latter node, and thus data can be held in the latter node even in a period during which supply of power source voltage is stopped. In the semiconductor device, a means of setting the potential of the latter node to a predetermined potential is provided. Specifically, a means of supplying a potential corresponding to “1” or “0” that is data stored in the latter node from the former node is provided.

Abstract: A semiconductor storage device which stops and resumes the supply of power supply voltage without the necessity of saving and returning a data signal between a volatile storage device and a nonvolatile storage device is provided. In the nonvolatile semiconductor storage device, the volatile storage device and the nonvolatile storage device are provided without separation. Specifically, in the semiconductor storage device, data is held in a data holding portion connected to a transistor including a semiconductor layer containing an oxide semiconductor and a capacitor. The potential of the data held in the data holding portion is controlled by a data potential holding circuit and a data potential control circuit. The data potential holding circuit can output data without leaking electric charge, and the data potential control circuit can control the potential of the data held in the data holding portion without leaking electric charge by capacitive coupling through the capacitor.

Abstract: A first field-effect transistor provided over a substrate in which an insulating region is provided over a first semiconductor region and a second semiconductor region is provided over the insulating region; an insulating layer provided over the substrate; a second field-effect transistor that is provided one flat surface of the insulating layer and includes an oxide semiconductor layer; and a control terminal are provided. The control terminal is formed in the same step as a source and a drain of the second field-effect transistor, and a voltage for controlling a threshold voltage of the first field-effect transistor is supplied to the control terminal.

Abstract: To provide a signal processing circuit including a nonvolatile memory circuit with a novel structure, the signal processing circuit includes an arithmetic portion, a memory, and a control portion for controlling the arithmetic portion and the memory. The control portion includes a set of a volatile memory circuit and a first nonvolatile memory circuit for storing data held in the volatile memory circuit, the memory includes a plurality of second nonvolatile memory circuits, and the first nonvolatile memory circuit and the second nonvolatile memory circuit each include a transistor having a channel in an oxide semiconductor layer and a capacitor in which one of a pair of electrodes is electrically connected to a node which is set in a floating state when the transistor is turned off.

Abstract: A first field-effect transistor provided over a substrate in which an insulating region is provided over a first semiconductor region and a second semiconductor region is provided over the insulating region; an insulating layer provided over the substrate; a second field-effect transistor that is provided one flat surface of the insulating layer and includes an oxide semiconductor layer; and a control terminal are provided. The control terminal is formed in the same step as a source and a drain of the second field-effect transistor, and a voltage for controlling a threshold voltage of the first field-effect transistor is supplied to the control terminal.

Abstract: The data in a volatile memory may conventionally be lost even in case of a very short time power down or supply voltage drop such as an outage or sag. In view of the foregoing, an object is to extend data retention time even with a volatile memory for high-speed data processing. Data retention time can be extended by backing up the data content stored in the volatile memory in a memory including a capacitor and an oxide semiconductor transistor.

Abstract: A semiconductor device with short overhead time. The semiconductor device includes a first wiring supplied with a power supply potential, a second wiring, a switch for controlling electrical connection between the first wiring and the second wiring, a load electrically connected to the second wiring, a transistor whose source and drain are electrically connected to the second wiring, and a power management unit having functions of controlling the conduction state of the switch and controlling a gate potential of the transistor. A channel formation region of the transistor is included in an oxide semiconductor film.

Abstract: The data in a volatile memory may conventionally be lost even in case of a very short time power down or supply voltage drop such as an outage or sag. In view of the foregoing, an object is to extend data retention time even with a volatile memory for high-speed data processing. Data retention time can be extended by backing up the data content stored in the volatile memory in a memory including a capacitor and an oxide semiconductor transistor.

Abstract: To provide a signal processing circuit including a nonvolatile memory circuit with a novel structure, the signal processing circuit includes an arithmetic portion, a memory, and a control portion for controlling the arithmetic portion and the memory. The control portion includes a set of a volatile memory circuit and a first nonvolatile memory circuit for storing data held in the volatile memory circuit, the memory includes a plurality of second nonvolatile memory circuits, and the first nonvolatile memory circuit and the second nonvolatile memory circuit each include a transistor having a channel in an oxide semiconductor layer and a capacitor in which one of a pair of electrodes is electrically connected to a node which is set in a floating state when the transistor is turned off.

Abstract: In a semiconductor device performing pipeline processing with the use of a reading portion reading an instruction and an arithmetic portion performing an operation in accordance with the instruction, the instruction held in the reading portion is transmitted from the flip-flop to the memory when branch prediction turns out to be wrong. Note that the arithmetic portion controls transmission and reception of the instruction between the flip-flop and the memory which are included in the reading portion. This enables elimination of redundant operations in the reading portion in the case where an instruction read by the reading portion after the branch prediction turns out to be wrong is a subroutine, or the like. That is, the instruction held in the memory is transmitted back to the flip-flop without rereading of the same instruction by the reading portion, whereby the instruction can be output to the arithmetic portion.

Abstract: In a semiconductor device including a control circuit and a memory, the memory includes at least a sector for preventing additional writing and an information sector. When data for preventing additional writing is written to the sector for preventing additional writing and information is written to the information sector which is electrically connected to the sector for preventing additional writing, additional writing to the information sector is impossible.

Abstract: When a CPU provided with a latch memory is operated, a constant storage method or an end storage method is selected depending on what is processed by the CPU; thus, the CPU provided with a latch memory has low power consumption. When the CPU provided with a latch memory is operated, in the case where the number of times of turning on and off the power source is high, a constant storage method is employed and in the case where the number of times of turning on and off the power source is low, an end storage method is employed. Whether a constant storage method or an end storage method is selected is determined based on the threshold value set depending on power consumption.

Abstract: To provide a signal processing circuit including a nonvolatile memory circuit with a novel structure, the signal processing circuit includes an arithmetic portion, a memory, and a control portion for controlling the arithmetic portion and the memory. The control portion includes a set of a volatile memory circuit and a first nonvolatile memory circuit for storing data held in the volatile memory circuit, the memory includes a plurality of second nonvolatile memory circuits, and the first nonvolatile memory circuit and the second nonvolatile memory circuit each include a transistor having a channel in an oxide semiconductor layer and a capacitor in which one of a pair of electrodes is electrically connected to a node which is set in a floating state when the transistor is turned off.

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 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.