Gilbert Decaens

Advanced ROICs design for cooled IR detectors

The CMOS silicon focal plan array technologies hybridized with infrared detectors materials allow to cover a wide range of applications in the field of space, airborne and grounded-based imaging. Regarding other industries which are also using embedded systems, the requirements of such sensor assembly can be seen as very similar; high reliability, low weight, low power, radiation hardness for space applications and cost reduction. Comparing to CCDs technology, excepted the fact that CMOS fabrication uses standard commercial semiconductor foundry, the interest of this technology used in cooled IR sensors is its capability to operate in a wide range of temperature from 300K to cryogenic with a high density of integration and keeping at the same time good performances in term of frequency, noise and power consumption. The CMOS technology roadmap predict aggressive scaling down of device size, transistor threshold voltage, oxide and metal thicknesses to meet the growing demands for higher levels of integration and performance. At the same time infrared detectors manufacturing process is developing IR materials with a tunable cut-off wavelength capable to cover bandwidths from visible to 20μm. The requirements of third generation IR detectors are driving to scaling down the pixel pitch, to develop IR materials with high uniformity on larger formats, to develop Avalanche Photo Diodes (APD) and dual band technologies. These needs in IR detectors technologies developments associated to CMOS technology, used as a readout element, are offering new capabilities and new opportunities for cooled infrared FPAs. The exponential increase of new functionalities on chip, like the active 2D and 3D imaging, the on chip analog to digital conversion, the signal processing on chip, the bicolor, the dual band and DTI (Double Time Integration) mode ...is aiming to enlarge the field of application for cooled IR FPAs challenging by the way the design activity.

Ultra-low power ADC on chip for high-performance IR detector

The InfraRed staring arrays developed by SOFRADIR are more and more compact and offer system solutions for wide range of IR wavebands. IR detectors have been taken to an even more advanced level of sophistication to achieve staring arrays high performances. Latest developments have also been focused on the silicon readout circuit. Digital conversion on chip is one of the recent progresses in this field of activity. In order to match each system requirements, on chip high performance ultra low power ADCs have been developed. Beyond the performance aspects, digital focal plane arrays can be considered as the first step towards low cost Dewar family, since they allow for a more simple electrical interface on Dewar designs and on chip image processing. Recent results concerning these new readout circuit architectures are presented in this paper.

Update on 10μm pixel pitch MCT-based focal plane array with enhanced functionalities

Sofradir was first to show a 10μm focal plane array (FPA) in DSS 2012, and announced the DAPHNIS 10μm product family back in 2014. This pixel pitch is key for enabling more compact sensors and increased resolution. SOFRADIR recently achieved outstanding MTF demonstration at this pixel pitch, which clearly demonstrate the benefit to users of adopting 10μm pixel pitch focal plane array based detectors. The last results, and associated gain in detection performance, are discussed in this paper. Concurrently to pitch downsizing, SOFRADIR also works on a global offer using digital interfaces and smart pixel functionalities. This opens the road to enhanced functionalities such as improved image quality, higher frame rate, lower power consumption and optimum operation for wide thermal conditions scenes. This paper also discusses these enhanced features and strategies allowing easier integration of the detector in the system.

Getting small: new 10μm pixel pitch cooled infrared products

Recent advances in miniaturization of IR imaging technology have led to a burgeoning market for mini thermalimaging sensors. Seen in this context our development on smaller pixel pitch has opened the door to very compact products. When this competitive advantage is mixed with smaller coolers, thanks to HOT technology, we achieve valuable reductions in size, weight and power of the overall package. In the same time, we are moving towards a global offer based on digital interfaces that provides our customers lower power consumption and simplification on the IR system design process while freeing up more space. Additionally, we are also investigating new wafer level camera solution taking advantage of the progress in micro-optics. This paper discusses recent developments on hot and small pixel pitch technologies as well as efforts made on compact packaging solution developed by SOFRADIR in collaboration with CEA-LETI and ONERA.

A comparative study of on chip decorrelation schemes for low power, high resolution infrared sensors

This paper discusses in-sensor decorrelation schemes for infrared applications. These applications require high image quality and low power consumption. Different scenarios involving analog and digital Haar discrete wavelet transform implementations are compared to classical quantization. High level modeling of image sensor shows that a simple decorrelation scheme can reduce column level power consumption while keeping high image quality.

New SOFRADIR 10μm pixel pitch infrared products

Recent advances in miniaturization of IR imaging technology have led to a growing market for mini thermal-imaging sensors. In that respect, Sofradir development on smaller pixel pitch has made much more compact products available to the users. When this competitive advantage is mixed with smaller coolers, made possible by HOT technology, we achieved valuable reductions in the size, weight and power of the overall package. At the same time, we are moving towards a global offer based on digital interfaces that provides our customers simplifications at the IR system design process while freeing up more space. This paper discusses recent developments on hot and small pixel pitch technologies as well as efforts made on compact packaging solution developed by SOFRADIR in collaboration with CEA-LETI.

Low IR input flux condition operations thanks to MCT e-APD

Low IR input flux conditions are answering different system applications as gas detection needs, active imagery, very long ranges detection and identification and some scientific applications. Then for other applications like ground applications, some system design trade-off could be made between thermal performance and identification and equipment size and cost.

On-chip data compression for I.R. image sensors

An IR imager read-out circuit embedding an enhanced decorrelation scheme based on first level Haar wavelet transform and predictive dynamic range estimation is proposed in this paper. This scheme provides lower power consumption, thanks to a reduced ADC resolution and a decreased output data-rate, at the expense of few reconstruction artifacts. A detailed circuit implementation is proposed and its limitations discussed.