Small pixel pitch, high-definition MWIR, and dual band SWIR/MWIR imaging sensors for SWaP-constrained applications

Hood, Andrew; Huang, Edward Kwei Wei; Yang, Kai; Hibberd, Dustin; Loung, Vincent Yong Kai; Oleson, Mitchell; Lott, Randall; Pratt, Charles S.; Thomas, J. A.; Costolo, Michael; MacDougal, M.H.

doi:10.1117/12.2664099

Cited by 3 publications

(1 citation statement)

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“…In recent years, there has been a trend in infrared imaging technology to reduce the pixel size, increase the resolution, decrease system costs, and enhance detector performance [ 1 , 2 ]. As infrared systems become increasingly compact, maintaining consistent system performance has emerged as a critical objective.…”

Section: Introductionmentioning

confidence: 99%

A 14-Bit Hybrid Analog-to-Digital Converter for Infrared Focal Plane Array Digital Readout Integrated Circuit

Hu,

Yao,

Chen

et al. 2024

Sensors

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This paper presents a 14-bit hybrid column-parallel compact analog-to-digital converter (ADC) for the application of digital infrared focal plane arrays (IRFPAs) with compromised power and speed performance. The proposed hybrid ADC works in two phases: in the first phase, a 7-bit successive approximation register (SAR) ADC performs coarse quantization; in the second phase, a 7-bit single-slope (SS) ADC performs fine quantization to complete the residue voltage conversion. In this work, the number of unit capacitors is reduced to 1/128th of that of a conventional 14-bit SAR ADC, which is beneficial for the application of small pixel-pitch IRFPAs. In this work, a tradeoff segmented thermometer-coded digital-to-analog converter (DAC) is adopted in the first 7-bit coarse quantization process: the lower 3-bit is binary coded, and the upper 4-bit is thermometer coded. A thermometer-coded DAC can improve the linearity of ADC. Capacitor array matching can be incredibly relaxed compared with a binary-weight 14-bit SAR ADC, resulting in a noncalibration feature. Moreover, by sharing DAC and comparator analog circuits between the SAR ADC and the SS ADC, the power consumption and layout area are consequently reduced. The proposed hybrid ADC was fabricated using a 180 nm CMOS process. The measurement results show that the proposed ADC has a differential nonlinearity of −0.61/+0.84 LSB and a sampling rate of 120 kS/s. The developed ADC achieves a temporal noise of 1.7 LSBrms at a temperature of 77 K. In addition, the SNDR is 72.9 dB, and the ENOB is 11.82 bit, respectively. Total power consumption is 71 μW from supply voltages of 3.3 V (analog) and 1.8 V (digital).

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Section: Introductionmentioning

confidence: 99%

A 14-Bit Hybrid Analog-to-Digital Converter for Infrared Focal Plane Array Digital Readout Integrated Circuit

Hu,

Yao,

Chen

et al. 2024

Sensors

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Detector size selection for long-range targeting performance in the extended shortwave infrared band

Wiley,

Katheder,

Follansbee

et al. 2024

Infrared Imaging Systems: Design, Analysis, Modeling, and Testing XXXV

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Interest in the eSWIR band is growing due to focal plane array technology advancements with mercury cadmium telluride and type-II superlattice materials. As design and fabrication processes improve, eSWIR detector size, weight, and power can now be optimized. For some applications, it is desirable to have a smaller detector size. Reduced solar illumination in the 2 to 2.5 µm spectral range creates a fundamental limit to passive imaging performance in the eSWIR band where the resolution benefit of small detectors cannot out-compete the reduced SNR in photon-starved environments. This research explores the underlying theory using signal-to-noise ratio radiometry and modeled target discrimination performance to assess the optimal detector size for eSWIR dependent upon illumination conditions. Finally, we model continuous-wave laser illumination in the eSWIR band to compare the effect of detector size on active and passive imaging for long-range object discrimination.

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A comparison of reflected and emitted radiometric signal levels in SWIR, eSWIR, MWIR, and superband (SWIR through MWIR) optical systems

Somerville,

Leslie,

Jordan

et al. 2024

Infrared Imaging Systems: Design, Analysis, Modeling, and Testing XXXV

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With the improvement of infrared detector technology over the last several decades, traditional design trades regarding the use of different wavebands in optical systems are becoming less and less applicable. New detector technology is allowing for extended and even bridged wavebands, where previous detectors were limited to only a single waveband. These bridged waveband cameras, or superband cameras, contain detectors with response over large spectral spans, allowing them to take advantage of the unique properties of multiple wavebands. This type of system is especially of interest when the superband contains both the short-wave infrared (SWIR) wavebandwhere most of the signal comes from reflected lightand midwave infrared (MWIR) wavebandwhere most of the signal comes from emitted light. Such a superband system allows the combination of reflected and emitted light on a single detector, opening new system level optical design trades across many fields and disciplines. Presented is a comparison of reflected and emitted radiometric signal levels for four filtered wavebands using a 1.5 μm to 5.4 μm superband imaging system: (1) with a 1.9 μm SWIR shortpass filter, (2) with a 2 μm to 2.5 μm extended SWIR (eSWIR) bandpass filter, (3) with a 3 μm MWIR longpass filter, and (4) with no filter (i.e., full superband response). The comparison in each of the four wavebands is repeated under four solar illumination conditions: full daylight, clouds, dusk, and night.

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Small pixel pitch, high-definition MWIR, and dual band SWIR/MWIR imaging sensors for SWaP-constrained applications

Cited by 3 publications

References 0 publications

A 14-Bit Hybrid Analog-to-Digital Converter for Infrared Focal Plane Array Digital Readout Integrated Circuit

A 14-Bit Hybrid Analog-to-Digital Converter for Infrared Focal Plane Array Digital Readout Integrated Circuit

Detector size selection for long-range targeting performance in the extended shortwave infrared band

A comparison of reflected and emitted radiometric signal levels in SWIR, eSWIR, MWIR, and superband (SWIR through MWIR) optical systems

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