Abstract:
An imaging device with low power consumption is provided. The pixel of the imaging device includes first and second photoelectric conversion elements, and first to fifth transistors. A cathode of the first photoelectric conversion element is electrically connected to the first transistor. An anode of a second photoelectric conversion element is electrically connected to the second transistor. Imaging data of a reference frame is obtained using the first photoelectric conversion element, and then imaging data of a difference detection frame is obtained using the second photoelectric conversion element. After the imaging data of the difference detection frame is obtained, a first potential that is a potential of a signal output from the pixel and a second potential that is a reference potential are compared. Whether or not there is a difference between the imaging data of the reference frame and the imaging data of the difference detection frame is determined using the first potential and the second potential.
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:
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:
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:
To provide a novel semiconductor device, a semiconductor device capable of operating at a high speed, or a semiconductor device with reduced area, or a semiconductor device with low power consumption. The semiconductor device which has a function of taking a moving image includes a pixel portion including a plurality of pixels, a first circuit, and a second circuit. Each of the plurality of pixels has a function of converting irradiation light to generate first data and a function of generating second data corresponding to a difference between the first data in a first frame period and the first data in a second frame period. The first circuit has a function of converting the second data into a digital signal and outputting the digital signal as compressed data of the moving image. The second circuit has a function of controlling output of the compressed data.
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:
Provided is a novel semiconductor device, a semiconductor device with reduced area, or a versatile semiconductor device. The semiconductor device includes a pixel portion including a first pixel, a second pixel, a third pixel, and a fourth pixel; a first switch and a second switch located outside the first to fourth pixels; a first wiring located outside the first to fourth pixels; a second wiring electrically connected to the first and second pixels; and a third wiring electrically connected to the third and fourth pixels. A first terminal of the first switch is electrically connected to the first wiring. A second terminal of the first switch is electrically connected to the second wiring. A first terminal of the second switch is electrically connected to the first wiring. A second terminal of the second switch is electrically connected to the third wiring.
Abstract:
To provide a control circuit in a DC-DC converter, which includes transistors with the same conductivity type. The control circuit generates a pulse signal (GS), and includes a hysteresis comparator, a logic unit, a digital-analog converter circuit, and a comparator. The hysteresis comparator converts a signal (FB) based on an output voltage of the DC-DC converter into a digital signal (comp). The logic unit generates, in accordance with the signal comp, a pulse width modulation signal (pwm) determining a pulse width of the signal GS. The logic unit also divides a reference clock signal to generate an m-bit (m is greater than or equal to 2) second digital signal. The digital-analog converter circuit converts the m-bit second digital signal into an analog signal to generate a 2m-level triangular wave signal. The comparator compares the signal pwm with the triangular wave signal to output the comparison result as the signal GS.
Abstract:
A solid-state imaging device with high productivity and improved dynamic range is provided. In the imaging device including a photoelectric conversion element having an i-type semiconductor layer, functional elements, and a wiring, an area where the functional elements and the wiring overlap with the i-type semiconductor in a plane view is preferably less than or equal to 35%, further preferably less than or equal to 15%, and still further preferably less than or equal to 10% of the area of the i-type semiconductor in a plane view. Plural photoelectric conversion elements are provided in the same semiconductor layer, whereby a process for separating the respective photoelectric conversion elements can be reduced. The respective i-type semiconductor layers in the plural photoelectric conversion elements are separated by a p-type semiconductor layer or an n-type semiconductor layer.
Abstract:
An imaging device with low power consumption is provided. The pixel of the imaging device includes first and second photoelectric conversion elements, and first to fifth transistors. A cathode of the first photoelectric conversion element is electrically connected to the first transistor. An anode of a second photoelectric conversion element is electrically connected to the second transistor. Imaging data of a reference frame is obtained using the first photoelectric conversion element, and then imaging data of a difference detection frame is obtained using the second photoelectric conversion element. After the imaging data of the difference detection frame is obtained, a first potential that is a potential of a signal output from the pixel and a second potential that is a reference potential are compared. Whether or not there is a difference between the imaging data of the reference frame and the imaging data of the difference detection frame is determined using the first potential and the second potential.