A semiconductor device that has low power consumption and is capable of performing arithmetic operation is provided. The semiconductor device includes first to third circuits and first and second cells. The first cell includes a first transistor, and the second cell includes a second transistor. The first and second transistors operate in a subthreshold region. The first cell is electrically connected to the first circuit, the first cell is electrically connected to the second and third circuits, and the second cell is electrically connected to the second and third circuits. The first cell sets current flowing from the first circuit to the first transistor to a first current, and the second cell sets current flowing from the second circuit to the second transistor to a second current. At this time, a potential corresponding to the second current is input to the first cell. Then, a sensor included in the third circuit supplies a third current to change a potential of the second wiring, whereby the first cell outputs a fourth current corresponding to the first current and the amount of change in the potential.

A semiconductor device that has low power consumption and is capable of performing arithmetic operation is provided. The semiconductor device includes first to third circuits and first and second cells. The first cell includes a first transistor, and the second cell includes a second transistor. The first and second transistors operate in a subthreshold region. The first cell is electrically connected to the first circuit, the first cell is electrically connected to the second and third circuits, and the second cell is electrically connected to the second and third circuits. The first cell sets current flowing from the first circuit to the first transistor to a first current, and the second cell sets current flowing from the second circuit to the second transistor to a second current. At this time, a potential corresponding to the second current is input to the first cell. Then, a sensor included in the third circuit supplies a third current to change a potential of the second wiring, whereby the first cell outputs a fourth current corresponding to the first current and the amount of change in the potential.

To provide a semiconductor device with a novel structure. The semiconductor device includes an accelerator. The accelerator includes a first memory circuit, a second memory circuit, and an arithmetic circuit. The first memory circuit includes a first transistor. The second memory circuit includes a second transistor. Each of the first transistor and the second transistor includes a semiconductor layer including a metal oxide in a channel formation region. The arithmetic circuit includes a third transistor. The third transistor includes a semiconductor layer including silicon in a channel formation region. The first transistor and the second transistor are provided in different layers. The layer including the first transistor is provided over a layer including the third transistor. The layer including the second transistor is provided over the layer including the first transistor. The data retention characteristics of the first memory circuit are different from those of the second memory circuit.

Novel connection between neurons of a neural network is provided. A perceptron included in the neural network includes a plurality of neurons; the neuron includes a synapse circuit and an activation function circuit; and the synapse circuit includes a plurality of memory cells. A bit line selected by address information for selecting a memory cell is shared by a plurality of perceptrons. The memory cell is supplied with a weight coefficient of an analog signal, and the synapse circuit is supplied with an input signal. The memory cell multiplies the input signal by the weight coefficient and converts the multiplied result into a first current. The synapse circuit generates a second current by adding a plurality of first currents and converts the second current into a first potential. The activation function circuit is a semiconductor device that converts the first potential into a second potential by a ramp function and supplies the second potential as an input signal of the synapse circuit included in the perceptron in a next stage.

A semiconductor device that enables lower power consumption and data storage imitating a human brain is provided. The semiconductor device includes a control unit, a memory unit, and a sensor unit. The memory unit includes a memory circuit and a switching circuit. The memory circuit includes a first transistor and a capacitor. The switching circuit includes a second transistor and a third transistor. The first transistor and the second transistor include a semiconductor layer including a channel formation region with an oxide semiconductor, and a back gate electrode. The control unit has a function of switching a signal supplied to the back gate electrode, in accordance with a signal obtained at the sensor unit.

A semiconductor device that enables lower power consumption and data storage imitating a human brain is provided. The semiconductor device includes a control unit, a memory unit, and a sensor unit. The memory unit includes a memory circuit and a switching circuit. The memory circuit includes a first transistor and a capacitor. The switching circuit includes a second transistor and a third transistor. The first transistor and the second transistor include a semiconductor layer including a channel formation region with an oxide semiconductor, and a back gate electrode. The control unit has a function of switching a signal supplied to the back gate electrode, in accordance with a signal obtained at the sensor unit.

A novel semiconductor device is provided. A structure body extending in a first direction, a first conductor extending in a second direction, and a second conductor extending in the second direction are provided. In a first intersection portion where the structure body and the first conductor intersect with each other, a first insulator, a first semiconductor, a second insulator, a second semiconductor, a third insulator, a fourth insulator, and a fifth insulator are provided concentrically around a third conductor. In a second intersection portion where the structure body and the second conductor intersect with each other, the first insulator, the first semiconductor, the second insulator, a fourth conductor, the second semiconductor, and the third insulator are provided concentrically around the third conductor.

A semiconductor device with a novel structure is provided. The semiconductor device includes a memory circuit including a first transistor and a second transistor. The first transistor is formed on a silicon substrate. The second transistor is formed in a layer above a layer where the first transistor is provided. The first transistor includes a first gate electrode and a first back gate electrode with a first channel formation region interposed therebetween. The first gate electrode is electrically connected to one of a source and a drain of the second transistor. The first back gate electrode is formed using a region where an impurity element imparting a conductivity type is selectively introduced in the silicon substrate. The second transistor includes a second channel formation region. The second channel formation region includes a metal oxide.

A memory device includes a plurality of memory cells. A first memory cell of the plurality of memory cells includes a first write transistor includes a first write gate, a first write source, and a first write drain. A first read transistor includes first read gate, a first read source, a first read drain, and a first body region separating the first read source from the first read drain. The first read source is coupled to the first write source. A first capacitor has a first upper capacitor plate coupled to the first write drain and a first lower capacitor plate coupled to the first body region of the first read transistor.

A low-power memory device in which a NAND flash memory and a controller are connected to each other with a short wiring, the controller and a cache memory are connected to each other with a short wiring, and signal transmission delay is small is provided. For example, the NAND flash memory is formed using a Si transistor formed with a single crystal silicon substrate. Since an OS transistor can be formed by a method such as a thin-film method, the cache memory formed using the OS memory can be stacked over the NAND flash memory. When the NAND flash memory and the cache memory are formed in one chip, the NAND flash memory and the controller can be connected to each other with a short wiring, and the controller and the cache memory can be connected to each other with a short wiring.