Semiconductor device and wireless tag using the same
First Claim
1. A semiconductor device comprising:
- a voltage detection circuit outputting a potential in accordance with a level of electric power supplied from an external portion;
a memory circuit holding a potential in accordance with a maximum value of the potential output from the voltage detection circuit; and
a protection circuit electrically connected to the memory circuit,wherein the memory circuit comprises a first transistor and a capacitor,wherein one of a source and a drain of the first transistor is electrically connected to one electrode of the capacitor, andwherein the other of the source and the drain of the first transistor is electrically connected to another electrode of the capacitor.
1 Assignment
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Accused Products
Abstract
In a wireless tag with which a wireless communication system whose electric power of a carrier wave from a R/W is high, an overvoltage protection circuit is provided to prevent from generating excessive electric power in the wireless tag when the wireless tag receives excessive electric power. However, as noise is generated by operation of the overvoltage protection circuit, an error of reception occurs in receiving a signal whose modulation factor is small. To solve the problem, the maximum value of generated voltage in the wireless tag is held in a memory circuit after the overvoltage protection circuit operates, then the overvoltage protection circuit is controlled in accordance with the maximum value of generated voltage. The voltages at which the overvoltage protection circuit starts and stops operating are different from each other, and hysteresis occurs between the timing when the overvoltage protection circuit starts and stops operating.
24 Citations
14 Claims
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1. A semiconductor device comprising:
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a voltage detection circuit outputting a potential in accordance with a level of electric power supplied from an external portion; a memory circuit holding a potential in accordance with a maximum value of the potential output from the voltage detection circuit; and a protection circuit electrically connected to the memory circuit, wherein the memory circuit comprises a first transistor and a capacitor, wherein one of a source and a drain of the first transistor is electrically connected to one electrode of the capacitor, and wherein the other of the source and the drain of the first transistor is electrically connected to another electrode of the capacitor. - View Dependent Claims (4, 5, 6, 9, 12)
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2. A semiconductor device comprising:
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a voltage detection circuit outputting a potential in accordance with a level of electric power supplied from an external portion; a memory circuit holding a potential in accordance with a maximum value of the potential output from the voltage detection circuit; and a protection circuit electrically connected to the memory circuit, wherein the memory circuit comprises a first transistor, a capacitor and a second transistor, wherein the protection circuit comprises a third transistor, wherein one of a source and a drain of the first transistor is electrically connected to one electrode of the capacitor, and wherein the other of the source and the drain of the first transistor is electrically connected to another electrode of the capacitor, wherein a gate and one of a source and a drain of the second transistor are electrically connected to the voltage detection circuit, wherein the other of the source and the drain of the second transistor is electrically connected to the one of the source and the drain of the first transistor, and wherein a gate of the third transistor is electrically connected to the one electrode of the capacitor. - View Dependent Claims (7, 10, 13)
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3. A semiconductor device comprising:
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an antenna circuit receiving electric power from an external portion; a voltage detection circuit outputting a potential in accordance with a level of the electric power; a memory circuit holding a potential in accordance with a maximum value of the potential output from the voltage detection circuit; and a protection circuit electrically connected to the memory circuit, wherein the memory circuit comprises a first transistor, a capacitor and a second transistor, wherein the protection circuit comprises a third transistor, wherein one of a source and a drain of the first transistor is electrically connected to one electrode of the capacitor, and wherein the other of the source and the drain of the first transistor is electrically connected to another electrode of the capacitor, wherein a gate and one of a source and a drain of the second transistor are electrically connected to the voltage detection circuit, wherein the other of the source and the drain of the second transistor is electrically connected to the one of the source and the drain of the first transistor, and wherein a gate of the third transistor is electrically connected to the one electrode of the capacitor. - View Dependent Claims (8, 11, 14)
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Specification