Analog optical black clamping circuit for a charge coupled device having wide programmable gain range
US6940548B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 27, 2001 |
| Grant date | Sep 6, 2005 |
| Priority date | — |
| Expiry date | Sep 28, 2023 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N25/633
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An image processing apparatus (200) for a charge coupled device including analog front end circuitry having optical black and offset correction, whereby the offset and optical black correction circuit is programmable. The present invention includes a first circuit (202, 204, 206, 208, 210) to sample the incoming optical black signal output from a CCD. This first circuit includes a correlated double sampler (202) coupled to a first programmable gain amplifier (204). An adder (206) connects between the first programmable gain amplifier (204) and a second gain amplifier (208) for adding in the optical black offset to the optical black signal input from the CCD. A second circuit (212, 214) includes a reverse programmable gain amplifier (212) connected to the output of the second programmable gain amplifier (208) to amplify the optical black level inversely proportional to the gain from the second programmable gain amplifier (208). The second circuit (212, 214) also includes an integrator (214) coupled to the reverse programmable gain amplifier (212) to integrate the difference between the incoming signal and the desired optical black value. The second circuit (212, 214) couples to the …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.