High sensitivity variable capacitance transducer
US4420790A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 2, 1982 |
| Grant date | Dec 13, 1983 |
| Priority date | — |
| Expiry date | Apr 2, 2002 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T29/435
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A semiconductor capacitance transducer includes adjoining integrated sensor and reference capacitance transducers formed from silicon wafers. The transducers are parallel plate transducers which are structurally the same except that one plate of the sensor transducer is a thin force sensing diaphragm which deflects in response to selected environmental phenomena while the corresponding plate of the reference transducer is adapted to deform in response to some, but not all, of the selected environmental phenomena. By comparing the capacitance of the transducers, the effects of the phenomena which deform the reference transducer can be distinguished from the effects of the phenomena which do not deform the reference transducer. A particular application of the present invention allows thermal effects on the sensor transducer to be distinguished from the effects of pressure. Also, the sensor and reference transducers are rendered substantially free from thermal stress by constructing their plates of the same semiconductor material and electrically isolating the plates with surface passivation layers.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.