Image Sensors – ISSCC2012
February 22, 2012, ISSCC, San Francisco—Image sensors built in CMOS have advanced to become the capture technology of choice in everything from cell phones through cinema. The challenges are to improve dynamic range, noise performance, capture 2-D and 3-D images, and operate at ever higher speeds.
Sony introduced a single exposure global shutter with in-pixel storage. The 5 M pixel image sensor has an extended dynamic range and low readout noise of 4.8 erms. The imager has internal storage node.
Tohoku University talked about their global shutter image sensor intended for extreme high speed video cameras running at up to 10M frames per second. The 400 x 256 pixel imager can output up to 1T pixels/s in burst mode, and 780 M pixels continuously.
Delft University of Technology showed a extremely low noise sensor for low light imaging. The imager combines in-pixel buried–channel source followers, column–level amplifiers and correlated multiple sampling resulting in 0.7e temporal readout noise.
Stanford University presented a 256×256 sensor with delta-sigma A/D conversion and on-chip compression. Performing the compression with the A/D conversion results in greatly reduced power consumption. Compression ratios of 1/4, 1/8, and 1/16 are achieved at 480, 960, and 1920 fps and power remains fairly constant compared to the standard 120 fps.
NHK uses a column-parallel pipelined ADC for the output of their 33 Mpixel 120 fps imager. The 7680×4320 pixel imager is designed for ultra-high definition (4k) TV. The converters are 2-stage column-parallel ADCs with 12 b precision. Aggregate data output is 51.2 Gb/s through 6-fold LVDS output ports and 96 total ports.
Samsung introduced three imagers. The first uses an extended count ADC to obtain two modes of operation. The ADC can achieve 12b resolution in a 6M pixel 36.5 fps video mode and 14b 24M pixel 10.2 fps still mode. The second paper described a 1.5M pixel RBGZ image sensor that captures color and time of flight to provide depth information that is captured simultaneously with the image. The z plane captures a 20 MHz modulated near-infrared illuminator image with the visible image. The third imager also uses time of flight to make a full 2-D HD image plus depth data.
Fondazione Bruno Kesssler submitted a QVGA range image sensor that is combined with 3 high brightness IR LEDs to obtain spatial resolution of less than 16 cm over a 0.8 to 7.5meter range at 8 fps. The range can be traded off with frame rate to get less than 15cm uncertainty in a 0.8 to 3m range at 25 fps.
