CMOS analog front end architecture with variable gain for digital cameras and camcorders
US6753913B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 1, 2000 |
| Grant date | Jun 22, 2004 |
| Priority date | — |
| Expiry date | Dec 15, 2022 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N25/78
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An image processing apparatus for charge coupled device (CCD) and video inputs in a digital camera or for a digital camcorder is disclosed which provides optical black and offset correction for CCD inputs. A sampling circuit, including correlated double sampler (CDS) (402) and programmable gain amplifier (450), samples the image input signal and the video input signal. CDS (402) includes a single-ended amplifier (404) and a differential amplifier (406). The single-ended amplifier (404) functions such that it is only operable during an CCD signal input; otherwise, the single-ended amplifier (404) is bypassed such that a video signal is only sampled by the differential amplifier (406). For CCD signals, the single-ended amplifier (404) samples the reference level of the pixel and holds it during the video interval. The differential amplifier (404) samples both the output of the single ended amplifier (404) and the video level of the same pixel. Overall, the CDS (402) subtracts these levels and converts the difference to a differential output to improve signal to noise performance and dynamic range. An analog-to-digital converter (210) converts the sampled signal and feeds this digital…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.