A readout IC for an uncooled microbolometer infrared FPA with on-chip self-heating compensation in 0.35 mu m CMOS
This paper describes a readout integrated circuit architecture for an infrared focal plane array intended for infrared network-attached video cameras in surveillance applications. The focal plane array consists of 352 x 288 uncooled thin-film microbolometer detectors with a pitch of 25 mu m, enabling ambient temperature operation. The circuit features a low-noise readout path, detector resistance mismatch correction and a non-linear ramped current pulse scheme for the electrical biasing of the detectors in order to relax the dynamic range requirement of amplifiers and the ADC in the readout channel, imposed by detector process variation and self-heating during readout. The design is implemented in a 0.35-mu m standard CMOS process and two versions of a smaller 32 x 32-pixel test chip have been fabricated and measured for evaluation. The latest test chip achieves a dynamic range of 97 dB and an input-referred RMS noise voltage of 6.4 mu V yielding an estimated NETD value of 26 mK with f/1 optics. At a frame rate of 60 FPS the chip dissipates 170 mW of power from a 3.4 V supply.
uncooled microbolometer self-heating compensation readout integrated circuit infrared imaging high-resolution data conversion bias heating compensation