Apparatus and method for reducing parasitic capacitive coupling and noise in fingerprint sensing circuits
US8005276B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 4, 2008 |
| Grant date | Aug 23, 2011 |
| Priority date | — |
| Expiry date | Apr 13, 2030 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06V40/1306
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A fingerprint sensing circuit for reducing noise and parasitic capacitive coupling is disclosed in one embodiment of the invention as including a plurality of transmitting elements to sequentially emit a probing signal. A digital ground is provided to ground digital components in the fingerprint sensing circuit. A quiet ground, separate from and quieter than the digital ground, is provided to ground transmitting elements that are not transmitting the probing signal. Similarly, control logic is provided to connect, to the quiet ground, transmitting elements that are not transmitting the probing signal, while disconnecting, from the quiet ground, transmitting elements that are emitting the probing signal. The quiet ground helps to reduce the adverse effects of parasitic capacitive coupling and noise on the inactive transmitting elements.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.