发明名称 |
Semiconductor device and driving method thereof |
摘要 |
There has been a problem in battryless RFID chips that a high voltage AC signal is generated when an antenna is exposed to a high electromagnetic field, and a DC voltage that is obtained through rectification of the AC signal becomes a high voltage accordingly. As a result, heat generation of a logic circuit and a clock generator circuit or element break down occur. The invention takes the following measures: a DC voltage generated through rectification of an AC signal is compared with a reference voltage in a comparator circuit, and a switch element is turned ON when the DC voltage becomes higher so as to add capacitance to an antenna circuit. Accordingly, resonance point of an antenna changes which in turn attenuates an AC signal generated in the antenna circuit, thereby suppressing a DC voltage.
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申请公布号 |
US7471188(B2) |
申请公布日期 |
2008.12.30 |
申请号 |
US20040003118 |
申请日期 |
2004.12.03 |
申请人 |
SEMICONDUCTOR ENERGY LABORATORY CO., LTD. |
发明人 |
KOYAMA JUN;SAITO TOSHIHIKO |
分类号 |
H03K19/00;H04Q5/22;G06K19/07;G06K19/077;H01L27/08 |
主分类号 |
H03K19/00 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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