摘要:
An object of one embodiment of the present invention is to propose a memory device in which a period in which data is held is ensured and memory capacity per unit area can be increased. In the memory device of one embodiment of the present invention, bit lines are divided into groups, and word lines are also divided into groups. The word lines assigned to one group are connected to the memory cell connected to the bit lines assigned to the one group. Further, the driving of each group of bit lines is controlled by a dedicated bit line driver circuit of a plurality of bit line driver circuits. In addition, cell arrays are formed on a driver circuit including the above plurality of bit line driver circuits and a word line driver circuit. The driver circuit and the cell arrays overlap each other.
摘要:
An object is to provide a three-dimensional display device capable of displaying bright images with low power consumption. The display device includes: an image display portion including a pixel portion provided with a plurality of pixels; a light-blocking portion including a first shutter and a second shutter; a signal source outputting the common potential; and a controller controlling transmittances of the first shutter and the second shutter and level of the common potential output from the signal source to bring the transmittances and the level into synchronism with supply of an image signal, display of a right-eye image, or display of a left-eye image performed in the pixel portion.
摘要:
It is an object of one embodiment of the present invention to manufacture a light-emitting display device by simplifying a manufacturing process of a transistor, without an increase in the number of steps as well as the number of photomasks as compared to those in the conventional case. A step for processing a semiconductor layer into an island shape is omitted by using a high-resistance oxide semiconductor which is intrinsic or substantially intrinsic for the semiconductor layer, used to form transistors. Formation of an opening in the semiconductor layer or an insulating layer formed over the semiconductor layer and etching of an unnecessary portion of the semiconductor layer are performed at the same time; thus, the number of photolithography steps is reduced.
摘要:
An object is to provide a semiconductor device having a novel structure, which can hold stored data even when not powered and which has an unlimited number of write cycles. A semiconductor device is provided with both a memory circuit including a transistor including an oxide semiconductor (in a broader sense, a transistor whose off-state current is sufficiently small) and a peripheral circuit such as a driver circuit including a transistor including a material other than an oxide semiconductor (in other words, a transistor capable of operating at sufficiently high speed). The peripheral circuit is provided in a lower portion and the memory circuit is provided in an upper portion; thus, the area and size of the semiconductor device can be decreased.
摘要:
An object is to provide a semiconductor device which includes a memory cell capable of holding accurate data even when the data is multilevel data. The semiconductor device includes a memory cell holding data in a node to which one of a source and a drain of a transistor whose channel region is formed from an oxide semiconductor. Note that the value of off-state current (leakage current) of the transistor is extremely small. Thus, after being set to have a predetermined value, the potential of the node can be kept constant or substantially constant by turning the transistor off. In this manner, accurate data can be stored in the memory cell.
摘要:
A memory device in which data can be retained for a long time is provided. The memory device includes a memory element and a transistor which functions as a switching element for controlling supply, storage, and release of electrical charge in the memory element. The transistor includes a second gate electrode for controlling the threshold voltage in addition to a normal gate electrode. Further, the off-state current of the transistor is extremely low because an active layer thereof includes an oxide semiconductor. In the memory device, data is stored not by injection of electrical charge to a floating gate surrounded by an insulating film at high voltage but by control of the amount of electrical charge of the memory element through the transistor whose off-state current is extremely low.
摘要:
Objects are to accumulate electric charge in a capacitor so that light intensity can be detected even when the amount of incident light is small, and to operate a photoelectric conversion device without increasing the number of elements such as a constant current source or a switch. The photoelectric conversion device includes a photoelectric conversion circuit, a capacitor, and a comparator for comparing a potential of one electrode of the capacitor with a second potential. The photoelectric conversion circuit includes a photoelectric conversion element and an amplifier circuit for amplifying an output current from the photoelectric conversion element In the capacitor, a first potential is supplied through a first switch, and charging or discharging is performed through a second switch in accordance with the current amplified by the amplifier circuit.
摘要:
There is provided a non-volatile memory which enables high accuracy threshold control in a writing operation. In the present invention, a drain voltage and a drain current of a memory transistor are controlled to carry out a writing operation of a hot electron injection system, which is wherein a charge injection speed does not depend on a threshold voltage. FIGS. 1A and 1B are views of a circuit structure for controlling the writing. In FIGS. 1A and 1B, an output of an operational amplifier 103 is connected to a control gate of a memory transistor 101, a constant current source 102 is connected to a drain electrode, and a source electrode is grounded. The constant current source 102 and a voltage Vpgm are respectively connected to two input terminals of the operational amplifier 103.
摘要:
The present invention is to provide a light emitting device capable of obtaining a certain luminance without influence by the temperature change, and a driving method thereof. A current mirror circuit formed by using a transistor is provided for each pixel. The first transistor and the second transistor of the current mirror circuit are connected such that the drain currents thereof are maintained at proportional values regardless of the load resistance value. Thereby, a light emitting device capable of controlling the OLED driving current and the luminance of the OLED by controlling the drain current of the first transistor at a value corresponding to a video signal in a driving circuit, and supplying the drain current of the second transistor to the OLED, is provided.
摘要:
To reduce power consumption of a semiconductor integrated circuit and to reduce delay of the operation in the semiconductor integrated circuit, a plurality of sequential circuits included in a storage circuit each include a transistor whose channel formation region is formed with an oxide semiconductor, and a capacitor whose one electrode is electrically connected to a node that is brought into a floating state when the transistor is turned off. By using an oxide semiconductor for the channel formation region of the transistor, the transistor with an extremely low off-state current (leakage current) can be realized. Thus, by turning off the transistor in a period during which power supply voltage is not supplied to the storage circuit, the potential in that period of the node to which one electrode of the capacitor is electrically connected can be kept constant or almost constant. Consequently, the above objects can be achieved.