30 May 1995 On-chip analog-to-digital conversion suitable for uncooled focal plane detector arrays employed in smart IR sensors
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This paper discusses a signal conditioning and analog-to-digital (A/D) conversion principle suitable for infrared detector arrays, especially for applications using uncooled bolometer thermal detectors. An experimental 16 X 16 array has been designed including a columnwise A/D conversion. The A/D conversion method is of general interest whenever low cost, high digital resolution, and moderate speed is desired. High resolution and linearity is obtained without trimming. The technique is similar to a sigmadelta converter, but there is no need for complex decimation filters. Row-by-row readout operation of the bolometer array is supported by the columnwise A/D conversion. The 16-column preamplifier and A/D converter structure has been implemented in a standard 0.8 micrometers CMOS process, with 40 micrometers column pitch. The resolution is expected to be 16 bits with a conversion time of 78 microsecond(s) , and the power consumption is estimated to be about 0.5 m for a single column including preamplifier and A/D conversion. MOS transistor 1/f-noise is suppressed by electrical chopping at the preamplifier input. The on-chip columnwise A/D conversion has considerable potential for smart IR cameras with on-chip bit-slice processor architectures. A flexible single chip digital camera may be achieved with the implemented structure, since the digital column data of the A/D converter array and the rows of the detector array can be selected randomly. A theoretical analysis is made of how the SNR is affected by different levels of signal conditioning parallelism. This analysis can be used for qualitative comparison between different architectures.
© (1995) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Christer Jansson, Christer Jansson, Ulf Ringh, Ulf Ringh, Kevin Charles Liddiard, Kevin Charles Liddiard, "On-chip analog-to-digital conversion suitable for uncooled focal plane detector arrays employed in smart IR sensors", Proc. SPIE 2474, Smart Focal Plane Arrays and Focal Plane Array Testing, (30 May 1995); doi: 10.1117/12.210578; https://doi.org/10.1117/12.210578


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