CMOS image sensor with pixel level gain control
US6757018B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Dec 18, 1998 |
| Grant date | Jun 29, 2004 |
| Priority date | — |
| Expiry date | Dec 18, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N25/78
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An image sensor and method of sensing an image provides a variable amplifier at each pixel, thereby expanding the dynamic range of the sensor. An image sensor core (500) comprises a plurality of pixel sensors (510). Each pixel sensor preferably includes a photosensitive element (310), a variable amplifier (312), and an analog-to-digital converter (“ADC”) (314). The ADC (512) includes a comparator (512) coupled to a latch/shift register (514). The comparator (512) receives the output of the variable amplifier (312) and a ramp signal and produces an output when the ramp signal exceeds the amplifier (312) output. The latch/shift register (514) latches a count signal corresponding to the ramp signal when triggered by the comparator (512). In operation, the photosensitive element (310) is exposed to light for a first integration period. The variable amplifier (312) amplifies the resulting photocharge by the maximum possible amount. The ADC (314) converts the photocurrent to a digital signal and latches the five most significant bits in memory (514). These five bits are provided in parallel to the variable amplifier (312) to set the amplification level. Then, the photosensiti…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.