发明名称 |
Digital technique for precise measurement of variable capacitance |
摘要 |
The present invention comprises a circuit for measuring the capacitive differences of small capacitors. The circuit comprises a reference capacitor and a sensor capacitor. Connected to one of the plates of each capacitor is a switch which connects the capacitors to one of two reference voltages. The other plate of the capacitors are connected to an input terminal of a voltage comparator. The comparator compares the input voltage with a third reference voltage. Differences in voltages detected by the comparator are applied to a feedback loop for generating an offset voltage at the input terminal. The offset voltage applied at the input terminal is proportional to the capacitive difference between the reference capacitor and the sensor capacitor. The feedback loop comprises a successive approximation register for digitizing the offset voltages and a digital to analog converter for converting the digitized voltages into analog voltages which are applied at the input terminal. Digitized offset voltages can be measured at the output of the successive approximation register.
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申请公布号 |
US4860232(A) |
申请公布日期 |
1989.08.22 |
申请号 |
US19870041773 |
申请日期 |
1987.04.22 |
申请人 |
MASSACHUSETTS INSTITUTE OF TECHNOLOGY |
发明人 |
LEE, HAE-SEUNG;HOWE, ROGER T.;KUNG, JOSEPH T. |
分类号 |
G01D5/241;G01L9/12;G01R17/06;G01R27/26 |
主分类号 |
G01D5/241 |
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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