A readout circuit for an uncooled IR camera with mismatch and self-heating compensation

Abstract

This paper presents a readout integrated circuit for an infrared focal plane array intended to be used in infrared network attached video cameras in surveillance applications. The focal plane array consists of 352×288 uncooled microbolometer detectors with a pitch of 25 μm. The circuit features mismatch correction and a non-linear ramped current pulse scheme for biasing of the detectors, in order to relax the dynamic range requirement of preamplifiers and ADC imposed by detector process variation and self-heating during readout. The integrated circuit is designed in a 0.35 μm standard CMOS process and a smaller 32×32 size test chip has been fabricated for verification. The test chip shows RMS input referred noise of 17 μV at 60 frames/second and dissipates 170 mW of power.