SEMICONDUCTOR DEVICE AND DRIVING METHOD OF SEMICONDUCTOR DEVICE
First Claim
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1. A semiconductor device comprising:
- a first transistor, wherein a gate of the first transistor is electrically connected to a first wiring;
a second transistor, wherein a gate of the second transistor is electrically connected to a second wiring which is different from the first wiring; and
a capacitor;
wherein one of the first transistor and the second transistor comprises oxide semiconductor,wherein the first transistor, the second transistor, and the capacitor are electrically connected in series,
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Abstract
A memory cell includes a capacitor, a first transistor, and a second transistor whose off-state current is smaller than that of the first transistor. The first transistor has higher switching speed than the second transistor. The first transistor, the second transistor, and the capacitor are electrically connected in series. Accumulation of charge in the capacitor and release of charge from the capacitor are performed through the first transistor and the second transistor. In this manner, the power consumption of the semiconductor device can be reduced and data can be written and read at higher speed.
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Citations
27 Claims
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1. A semiconductor device comprising:
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a first transistor, wherein a gate of the first transistor is electrically connected to a first wiring; a second transistor, wherein a gate of the second transistor is electrically connected to a second wiring which is different from the first wiring; and a capacitor; wherein one of the first transistor and the second transistor comprises oxide semiconductor, wherein the first transistor, the second transistor, and the capacitor are electrically connected in series, - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A semiconductor device comprising:
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a plurality of memory cells, each of the plurality of memory cells comprising; a first transistor, wherein a gate of the first transistor is electrically connected to one of a plurality of first word lines; a second transistor, wherein a gate of the second transistor is electrically connected to one of a plurality of second word lines which is different from the plurality of first word lines; and a capacitor; wherein one of the first transistor and the second transistor comprises oxide semiconductor, wherein the first transistor and the second transistor are electrically connected in series between the capacitor and one of a plurality of bit lines. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A method for driving a semiconductor device, the semiconductor device comprising:
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a first transistor, wherein a gate of the first transistor is electrically connected to a first wiring; a second transistor, wherein a gate of the second transistor is electrically connected to a second wiring; and a capacitor; wherein one of the first transistor the second transistor comprises oxide semiconductor, and wherein the first transistor, the second transistor, and the capacitor are electrically connected in series, the method comprising the steps of; in a first mode, turning off the other of the first transistor and the second transistor to store a charge in the capacitor, and in a second mode, turning off both of the first transistor and the second transistor to store a charge in the capacitor. - View Dependent Claims (26)
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27. A method for driving a semiconductor device, the semiconductor device comprising:
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a plurality of memory cells, each of the plurality of memory cells comprising; a first transistor, wherein a gate of the first transistor is electrically connected to one of a plurality of first word lines; a second transistor, wherein a gate of the second transistor is electrically connected to one of a plurality of second word lines which is different from the plurality of first word lines; and a capacitor; wherein one of the first transistor and the second transistor comprises oxide semiconductor, and wherein the first transistor and the second transistor are electrically connected in series between the capacitor and one of a plurality of bit lines, the method comprising the steps of in a first mode, turning on the one of the first transistor and the second transistor in each of the plurality of memory cells and the other of the first transistor and the second transistor in one of the plurality of memory cells to accumulate a charge in or release a charge from the capacitor in one of the plurality of memory cells in which both of the first transistor and the second transistor are on; and in a second mode, turning on the first transistor and the second transistor in one of the plurality of memory cells to accumulate a charge in or release a charge from the capacitor in one of the plurality of memory cells in which both of the first transistor and the second transistor are on.
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Specification