Abstract: An imaging device whose dynamic range is broadened is provided. The imaging device includes a pixel including a first photoelectric conversion element and a first circuit including a second photoelectric conversion element. The first circuit switches the operation mode of the pixel to a normal imaging mode or a wide dynamic range mode and switches the operation region of the first photoelectric conversion element to a normal region or an avalanche region in accordance with the illuminance of light with which the second photoelectric conversion element is irradiated. When the illuminance of light with which the first photoelectric conversion element is irradiated is increased, the increase rate of a writing current flowing to the pixel is higher in the avalanche region than in the normal region. However, in the wide dynamic range mode, the increase rate of current can be lowered, and thus the dynamic range can be broadened.

Abstract: An imaging device capable of obtaining high-quality imaging data is provided. The imaging device can correct variation in the threshold voltage of amplifier transistors included in pixel circuits. The amplifier transistor includes two gates facing each other with a channel formation region provided therebetween. The amplifier transistor operates in such a manner that one of the gates holds a potential for correcting variation in the threshold voltage and the other thereof is supplied with a potential corresponding to imaging data.

Abstract: An imaging device with high productivity and improved dynamic range is provided. The imaging device includes a pixel driver circuit and a photoelectric conversion element including a p-type semiconductor, an n-type semiconductor, and an i-type semiconductor. In a plan view, the total area of a part of the i-type semiconductor overlapped with neither a metal material nor a semiconductor material constituting the pixel driver circuit is preferably greater than or equal to 65%, more preferably greater than or equal to 80%, and still more preferably greater than or equal to 90% of the area of the whole i-type semiconductor. Plural photoelectric conversion elements are provided in the same semiconductor, whereby a process for separating the photoelectric conversion elements can be omitted. The i-type semiconductors in the plural photoelectric conversion elements are separated from each other by the p-type semiconductor or the n-type semiconductor.

Abstract: To provide a memory device with short overhead time and a semiconductor device including the memory device. A memory device includes a first circuit that can retain data and a second circuit by the supply of power supply voltage. The second circuit includes a third circuit that selects a first potential corresponding to the data or a second potential supplied to a first wiring; a first transistor having a channel formation region in an oxide semiconductor film; a capacitor that hold the first potential or the second potential that is selected by the third circuit and supplied through the first transistor; and a second transistor controlling a conduction state between the first circuit and a second wiring that can supply a third potential in accordance with the potential retained in the capacitor.

Abstract: An object is to provide a memory element having a novel structure where data can be held even after power supply is stopped. The memory element includes a latch circuit, a first selection circuit, a second selection circuit, a first nonvolatile memory circuit, and a second nonvolatile memory circuit. The first nonvolatile memory circuit and the second nonvolatile memory circuit each include a transistor and a capacitor. The transistor included in each of the first nonvolatile memory circuit and the second nonvolatile memory circuit is a transistor in which a channel is formed in an oxide semiconductor film. The off-state current of such a transistor is extremely small. The transistor is turned off after data is input to a node where the transistor and the capacitor are connected to each other, and data can be held for a long time even after supply of power supply voltage is stopped.

Abstract: A semiconductor device includes a first transistor which includes a first gate electrode below its oxide semiconductor layer and a second gate electrode above its oxide semiconductor layer, and a second transistor which includes a first gate electrode above its oxide semiconductor layer and a second gate electrode below its oxide semiconductor layer and is provided so as to at least partly overlap with the first transistor. In the semiconductor device, a conductive film serving as the second gate electrode of the first transistor and the second gate electrode of the second transistor is shared between the first transistor and the second transistor. Note that the second gate electrode not only controls the threshold voltages (Vth) of the first transistor and the second transistor but also has an effect of reducing interference of an electric field applied from respective first gate electrodes of the first transistor and the second transistor.

Abstract: An imaging device whose dynamic range can be wide with a simple structure is provided. In a circuit configuration and an operation method of the imaging device, whether a charge detection portion provided in a pixel is saturated with electrons is determined and an operation mode is changed depending on the determination result. First imaging data is captured first, and is read out in the case where the charge detection portion is not saturated with electrons. In the case where the charge detection portion is saturated with electrons, the saturation of the charge detection portion is eliminated and second imaging data is captured and read out.

Abstract: An imaging device includes a pixel; a digital circuit; and an analog processing circuit including a constant current circuit, a current comparison circuit, and a control circuit. The pixel is capable of outputting differential data. The constant current circuit is capable of supplying a first current corresponding to the differential data, in accordance with a first control signal. The current comparison circuit is capable of supplying a second current that flows through the constant current circuit in accordance with a change in the differential data. The current comparison circuit has a function of setting a determination signal active depending on whether to supply the second current to the constant current circuit. The control circuit has a function of controlling the constant current circuit and the current comparison circuit to stop their functions as the determination signal becomes active. The digital circuit operates as the determination signal becomes active.

Abstract: An imaging device whose dynamic range is broadened is provided. The imaging device includes a pixel including a first photoelectric conversion element and a first circuit including a second photoelectric conversion element. The first circuit switches the operation mode of the pixel to a normal imaging mode or a wide dynamic range mode and switches the operation region of the first photoelectric conversion element to a normal region or an avalanche region in accordance with the illuminance of light with which the second photoelectric conversion element is irradiated. When the illuminance of light with which the first photoelectric conversion element is irradiated is increased, the increase rate of a writing current flowing to the pixel is higher in the avalanche region than in the normal region. However, in the wide dynamic range mode, the increase rate of current can be lowered, and thus the dynamic range can be broadened.

Abstract: In the case where a still image is displayed on a pixel portion having a pixel, for example, a driver circuit for controlling writing of an image signal having image data to the pixel portion stops by stopping supply of power supply voltage to the driver circuit, and writing of an image signal to the pixel portion is stopped. After the driver circuit stops, supply of power supply voltage to a panel controller for controlling the operation of the driver circuit and an image memory for storing the image data is stopped, and supply of power supply voltage to a CPU for collectively controlling the operation of the panel controller, the image memory, and a power supply controller for controlling supply of power supply voltage to a variety of circuits in a semiconductor display device is stopped.

Abstract: A semiconductor device including a register controller and a processor which includes a register is provided. The register includes a first circuit and a second circuit which includes a plurality of memory portions. The first circuit and the plurality of memory portions can store data by an arithmetic process of the processor. Which of the plurality of memory portions the data is stored in depends on a routine by which the data is processed. The register controller switches the routine in response to an interrupt signal. The register controller can make any one of the plurality of memory portions which corresponds to the routine store the data in the first circuit every time the routine is switched. The register controller can make data stored in any one of the plurality of memory portions which corresponds to the routine be stored in the first circuit every time the routine is switched.

Abstract: A small semiconductor device suitable for high-speed operation is provided. The semiconductor device includes a first circuit, a global bit line pair for writing, a global bit line pair for reading, and a local bit line pair. The first circuit includes second to fifth circuits. The second to fifth circuits are electrically connected to each other by the local bit line pair. The second circuit functions as a read/write selection switch. The third circuit functions as a working memory that stores 1-bit complementary data temporarily. The fourth circuit has a function of precharging the local bit line pair. The fifth circuit includes n (n is an integer of 2 or more) sixth circuits. The sixth circuits each have a function of retaining 1-bit complementary data written from the third circuit.

Abstract: An imaging device whose dynamic range is broadened is provided. The imaging device includes a pixel including a first photoelectric conversion element and a first circuit including a second photoelectric conversion element. The first circuit switches the operation mode of the pixel to a normal imaging mode or a wide dynamic range mode and switches the operation region of the first photoelectric conversion element to a normal region or an avalanche region in accordance with the illuminance of light with which the second photoelectric conversion element is irradiated. When the illuminance of light with which the first photoelectric conversion element is irradiated is increased, the increase rate of a writing current flowing to the pixel is higher in the avalanche region than in the normal region. However, in the wide dynamic range mode, the increase rate of current can be lowered, and thus the dynamic range can be broadened.

Abstract: Provided is an imaging device operated at high speed and low power consumption. The imaging device includes a pixel and a first circuit. The pixel includes a first photoelectric conversion element and a second photoelectric conversion element. The first circuit is configured to compare a first signal which is output from the pixel on the basis of imaging data obtained by the first photosensitive conversion element to a second signal which is output from the pixel on the basis of imaging data obtained by the second photosensitive conversion element for determining whether there is a difference between the first signal and the second signal. Thus, edge detection can be performed without a periphery device for edge detection outside the imaging device.

Abstract: A signal processing circuit whose power consumption can be suppressed is provided. In a period during which a power supply voltage is not supplied to a storage element, data stored in a first storage circuit corresponding to a nonvolatile memory can be held by a first capacitor provided in a second storage circuit. With the use of a transistor in which a channel is formed in an oxide semiconductor layer, a signal held in the first capacitor is held for a long time. The storage element can accordingly hold the stored content (data) also in a period during which the supply of the power supply voltage is stopped. A signal held by the first capacitor can be converted into the one corresponding to the state (the on state or off state) of the second transistor and read from the second storage circuit. Consequently, an original signal can be accurately read.

Abstract: A memory device with a novel structure that is suitable for a register file is provided. The memory device includes a first memory circuit and a second memory circuit. The first memory circuit includes a first logic element and a second logic element each of which is configured to perform logic inversion, a selection circuit, a first switch, a second switch, and a third switch. The second memory circuit includes a first transistor in which a channel formation region is provided in an oxide semiconductor film, a second transistor, and a capacitor to which a potential is supplied through the first transistor.

Abstract: A power supply circuit includes: an analog/digital converter for converting an analog signal to a digital signal; a pulse width modulation signal control circuit for generating a setting control signal varying in accordance with the difference between a reference voltage and a feedback voltage and a control signal for controlling a pulse width modulation signal, which is based on the digital signal; and a pulse width modulation signal generation circuit for generating the pulse width modulation signal, to which the count signal and the control signal are input, in which the control signal controls the duty cycle of the pulse width modulation signal, and the setting control signal controls the cycle of updating the duty cycle of the pulse width modulation signal.

Abstract: To provide an imaging device capable of high-speed reading. The imaging device includes a photodiode, a first transistor, a second transistor, a third transistor, and a fourth transistor. The back gate electrode of the first transistor is electrically connected to a wiring that can supply a potential higher than a source potential of the first transistor and a potential lower than the source potential of the first transistor. The back gate electrode of the second transistor is electrically connected to a wiring that can supply a potential higher than a source potential of the second transistor. The back gate electrode of the third transistor is electrically connected to a wiring that can supply a potential higher than a source potential of the third transistor and a potential lower than the source potential of the third transistor.

Abstract: An object is to obtain a rectifier having a small voltage drop and to reduce the fabrication cost of a converter circuit. A photoelectric transducer device including: a photoelectric transducer element; and a converter circuit stepping up or stepping down an output of the photoelectric transducer element and including a switching element and a rectifier, in which the switching element is a first oxide semiconductor transistor that is normally off and in which the rectifier is a second oxide semiconductor transistor that is diode-connected and normally on.

Abstract: A small semiconductor device suitable for high-speed operation is provided. The semiconductor device includes a first circuit, a global bit line pair for writing, a global bit line pair for reading, and a local bit line pair. The first circuit includes second to fifth circuits. The second to fifth circuits are electrically connected to each other by the local bit line pair. The second circuit functions as a read/write selection switch. The third circuit functions as a working memory that stores 1-bit complementary data temporarily. The fourth circuit has a function of precharging the local bit line pair. The fifth circuit includes n (n is an integer of 2 or more) sixth circuits. The sixth circuits each have a function of retaining 1-bit complementary data written from the third circuit.