Impedance detection circuit, impedance detection device, and impedance detection method
US6756790B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 3, 2001 |
| Grant date | Jun 29, 2004 |
| Priority date | — |
| Expiry date | Jan 31, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R27/02
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A second operational amplifier (11) of a core unit (1) shorts an inverting input terminal and an output terminal. A signal line (19) is connected to a non-inverting input terminal. A capacitive sensor (18) is connected to the signal line (19). A first operational amplifier (12) earths the non-inverting input terminal. One end of a first resistance (15) and one end of a second resistance (16) are respectively connected to the inverting input terminal. The other end of the first resistance (15) is connected to an alternate current voltage generator (14). The other end of the second resistance (16) is connected to the output terminal of the first operational amplifier (11). A signal output terminal (21) of the core unit (1) is connected to an inverting amplification device (2). An alternate output terminal (22) of the core unit (1) and an inverting output terminal (42) of the inverting amplification device (2) are connected to an addition device (3). The non-inverting input terminal of operational amplifiers (36) and (40).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.