Capacitive sensing analog front end
US9244569B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 17, 2010 |
| Grant date | Jan 26, 2016 |
| Priority date | — |
| Expiry date | Oct 1, 2034 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F3/0446
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A capacitive sensing analog front end for a touchscreen system having an improved signal-to-noise ratio includes a capacitance-to-voltage converter having an input for coupling to an external sampling capacitor, a summer having a first input coupled to an output of the capacitance-to-voltage converter, a low pass filter having an input coupled to an output of the summer and an output for providing an output signal; and a sample-and-hold circuit having an input coupled to the output of the low pass filter and an output coupled to a second input of the summer. The signal-to-noise ratio of the touchscreen system is improved by extracting the DC shift of a touch signal during a monitoring period and then subtracting the DC shift before integrating the touch signal.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.