Column amplifier with automatic gain selection for CMOS image sensors
US7443435B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Jul 7, 2004 |
| Grant date | Oct 28, 2008 |
| Priority date | — |
| Expiry date | Jul 24, 2026 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N25/78
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A column amplifier architecture having automatic gain selection for CMOS image sensors, which reduces the effect of analog noise, while maintaining a system's dynamic range. A comparator compares an amplified column buffer output signal to a reference voltage. The output of the comparator controls the gain of the amplifier based on the result of the comparison. Initially, a high column buffer gain is selected. For small signals, the output of the column buffer stays below the reference voltage and the output signal stays within the system's dynamic range. For larger signals, the column buffer output will exceed the reference voltage (and also the system's dynamic range) and therefore the comparator output switches states, which selects the low-gain setting. Multiple gain levels may be implemented, if desired.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.