A 256x512 element digital image sensor has been developed which has a large pixel size, slow scan and low power
consumption for Hyper Spectral Imager (HySI) applications. The device is a mixed mode, silicon on chip (SOC) IC. It
combines analog circuitry, digital circuitry and optical sensor circuitry into a single chip. This chip integrates a 256x512
active pixel sensor array, a programming gain amplifier (PGA) for row wise gain setting, I2C interface, SRAM, 12 bit
analog to digital convertor (ADC), voltage regulator, low voltage differential signal (LVDS) and timing generator. The
device can be used for 256 pixels of spatial resolution and 512 bands of spectral resolution ranged from 400 nm to 950
nm in wavelength. In row wise gain readout mode, one can set a different gain on each row of the photo detector by
storing the gain setting data on the SRAM thru the I2C interface. This unique row wise gain setting can be used to
compensate the silicon spectral response non-uniformity problem. Due to this unique function, the device is suitable for
hyper-spectral imager applications. The HySI camera located on-board the Chandrayaan-1 satellite, was successfully
launched to the moon on Oct. 22, 2008. The device is currently mapping the moon and sending back excellent images of
the moon surface. The device design and the moon image data will be presented in the paper.
Conventional space sensors have traditionally used CCD image sensors. Since CCD sensors provide analog output
signals, the camera system has needed to integrate additional analog and digital circuitry including CCD drivers. The
result is a camera that weighs more than 30 kg and dissipates more than 10 Watts of power. We report using an
advanced semiconductor technology to integrate CMOS image sensors, analog and digital circuitry together into a single
silicon chip. A Terrain Mapping Camera (TMC) was designed using this approach. The entire camera weighs less than
7 kg and dissipates only 1.8 Watts of power. The TMC was recently launched into moon orbit on October 22, 2008
aboard Chandrayaan-1. The image quality sent back from the TMC is excellent. Radiation testing of the digital image
sensor was conducted prior to launch with the device enduring more than 300 kilo-rads.
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