OmniVision's 1/4-Inch, 3-Megapixel Camera Chip

The ever more demanding digital camera users of the world keep the manufacturers on their toes, constantly producing new models. However, what many users don’t realize is that increased performance is primarily in the chips. OmniVision Technologies, Inc., a supplier of CMOS image sensors for high-volume applications, has launched the OV3640, a fully integrated 3-megapixel CameraChip sensor in a 1/4" format. Based on the new 1.75-micron OmniPixel3 architecture, the OV3640 is small enough to fit the standard 8 x 8 mm sockets used in 2-megapixel camera phones.

The OV3640 features a high-speed, two-lane mobile industry processor interface (MIPI) to enable the transfer of large blocks of data, which is critical to making effective use of increased camera resolutions. In addition, the new sensor incorporates advanced image signal processing and onboard JPEG compression to allow existing baseband processors without MIPI to support a camera upgrade to 3-megapixels at 15 frames per second in full resolution.

In addition to MIPI, the OV3640 also incorporates image stabilization functionality similar to that used in digital still camera (DSC) and camcorder products. In low-light situations, cameras need a longer exposure time, which, in turn, requires the photographer to keep a steady hand. Camera phones with an OV3640 sensor will automatically sense the slightest camera shake and activate the image stabilization function to help prevent image blur and produce sharper images.

The new features and improvements incorporated in the OV3640 are focused specifically on improving image quality and camera performance, both critical drivers for market acceptance of higher resolution cameras in the handset market. These new features and improvements include a new read-out circuit for reduced noise ; improved high resolution image signal processing for better overall camera performance and image quality ; a black level follower for stronger image contrast ; easy black level calibration to eliminate the need for gain adjust ; integrated auto-focus control for 8.5 x 8.5 mm auto focus camera modules and improved scaling to facilitate smooth zoom function.

The OV3640 is the first product launched by OmniVision based on the recently-announced OmniPixel3 architecture, which, at 1.75 microns is among the smallest currently commercially available. OmniPixel3 is designed to focus light onto the sensor more effectively, allowing the pixels to capture more light and make more effective use of the smaller pixel’s active area. OmniVision says the resulting improved fill factor and increased sensitivity deliver more vibrant and true-to-life color reproduction. OmniPixel3’s optimized pixel symmetry avoids color distortion and offers an improved dynamic range of up to 65dB. New process technology optimizations help OmniPixel3 achieve ultra low dark current (30 e/sec) and low defect density, improving performance in low light and variable light conditions. Further innovations include a new transfer gate design process and contact technologies that achieve lag-free operation throughout the signal range. Eliminating read-out lag ensures that no ’ghost images’ or unwanted noise are present in the imaging process.

The OV3640 is currently available for customer sampling. Volume production is expected by Q4 of 2007.