Proceedings Article | 6 December 1999
Proc. SPIE. 3759, Infrared Spaceborne Remote Sensing VII
KEYWORDS: CMOS sensors, Clocks, Sensors, Interfaces, Photodiodes, Image sensors, Transistors, Integrated circuits, Analog electronics, Imaging arrays
The detection of incipient wildfires from space is optimized by high spatial resolution, redundant coverage of a large swath, modest spectral resolution, and a high image frame rate. The desired information rate can exceed 109 bytes/sec, which is difficult to achieve with conventional sensor designs. A design is described for a distributed sensor consisting of 102 - 103 identical detection modules linked by a serial bus to a central controller. Each detection module or 'chipxel' contains an intelligent bus interface, a detector array, a multiplexer, amplifiers, digitizers, local data and program memory, a local controller, and modest image reprocessing. Clock, timing, and power control can also be present. The baseline detector element is an active CMOS image sensor, although a mix of detectors can share a common readout structure. The paper will describe the specifications for a two-chip implementation of a chipxel for space-based wildfire detection, with emphasis on the intelligent bus interface, power control, and on-chip preprocessing. Key analog and digital elements of the chip have been implemented in CMOS 0.35 micrometer technology, while ancillary functions and design augmentations can be evaluated in a gate array or similar hardware.
