One terminal capacitor interface circuit
US7235983B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 8, 2006 |
| Grant date | Jun 26, 2007 |
| Priority date | — |
| Expiry date | Mar 8, 2026 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M3/458
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A one terminal capacitor interface circuit for sensing the capacitance of a capacitor includes a differential integrating amplifier having an input common mode voltage and two summing nodes whose voltage is substantially equal to the input common mode voltage, a switching circuit for charging the capacitor to a first voltage level in a first phase, connecting, in a second phase, the capacitor to one of the summing nodes of the differential amplifier to provide a first output change substantially representative of the difference between the first voltage level and the input common mode voltage, and also representative of the capacitor; charging the capacitor to a second voltage level in a third phase, and connecting, in a fourth phase, the capacitor to the other summing node of the differential amplifier to provide a second output change substantially representative of the difference between the second voltage level and the input common mode voltage, and also representative of the capacitor; the combined first and second output changes representing the capacitance of the capacitor substantially independent of the input common mode voltage.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.