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Proceedings Paper

On-chip analog-to-digital conversion suitable for uncooled focal plane detector arrays employed in smart IR sensors
Author(s): Christer Jansson; Ulf Ringh; Kevin Charles Liddiard
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Paper Abstract

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.

Paper Details

Date Published: 30 May 1995
PDF: 16 pages
Proc. SPIE 2474, Smart Focal Plane Arrays and Focal Plane Array Testing, (30 May 1995); doi: 10.1117/12.210578
Show Author Affiliations
Christer Jansson, Linkoping Univ. (Sweden)
Ulf Ringh, National Defence Research Establishment (Sweden)
Kevin Charles Liddiard, DSTO (Australia)

Published in SPIE Proceedings Vol. 2474:
Smart Focal Plane Arrays and Focal Plane Array Testing
Marc Wigdor; Mark A. Massie, Editor(s)

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