Method and apparatus for capacitance sensing
US8344928B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 10, 2010 |
| Grant date | Jan 1, 2013 |
| Priority date | — |
| Expiry date | Jan 14, 2031 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M3/456
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A capacitance-to-digital converter for an extended range of capacitances includes a reference capacitor and one or more offset capacitors. Electrical charge accumulated in the offset capacitors is used to at least partially cancel the charge accumulated in a sensed capacitance to facilitate matching with a charge accumulated in the reference capacitor. The residual charge is passed to an integrator, the output from which is quantized and used to control switching of the capacitors. Immunity to tonal external noises and improved conversion speed are achieved by controlling the capacitor switching with a spread spectrum clock. The capacitance-to-digital converter may be used, for example, for sensing of the capacitances of capacitive elements in touch and proximity displays or other user interfaces.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.