Miniature curved artificial compound eyes.

International audienceIn most animal species, vision is mediated by compound eyes, which offer lower resolution than vertebrate single-lens eyes, but significantly larger fields of view with negligible distortion and spherical aberration, as well as high temporal resolution in a tiny package. Compound eyes are ideally suited for fast panoramic motion perception. Engineering a miniature artificial compound eye is challenging because it requires accurate alignment of photoreceptive and optical components on a curved surface. Here, we describe a unique design method for biomimetic compound eyes featuring a panoramic, undistorted field of view in a very thin package. The design consists of three planar layers of separately produced arrays, namely, a microlens array, a neuromorphic photodetector array, and a flexible printed circuit board that are stacked, cut, and curved to produce a mechanically flexible imager. Following this method, we have prototyped and characterized an artificial compound eye bearing a hemispherical field of view with embedded and programmable low-power signal processing, high temporal resolution, and local adaptation to illumination. The prototyped artificial compound eye possesses several characteristics similar to the eye of the fruit fly Drosophila and other arthropod species. This design method opens up additional vistas for a broad range of applications in which wide field motion detection is at a premium, such as collision-free navigation of terrestrial and aerospace vehicles, and for the experimental testing of insect vision theories

Characterization of Soft Error Rate Against Memory Elements Spacing and Clock Skew in a Logic with Triple Modular Redundancy in a 65nm Process

International audienceSingle Event Effects introduce soft errors in ASICs. Design methodologies like Triple ModularRedundancy (TMR) with clock skew insertion, a system level redundancy technique is a commonpractice by designers to mitigate soft errors. However, the optimal spacing between memoryelements in a TMR in 65nm process hasn't been addressed so far. RD53SEU is a mini ASICdevelopment under the framework of the CERN RD53 collaboration to characterize the soft errorrates against the separation spacing and clock skew between memory elements in a TMR. Thisarticle describes the architecture and design aspects of the various test structures on the RD53SEUtest chip

Single event effects testing of the RD53B chip

International audienceThe RD53 collaboration has been working since 2014 on the development of pixel chips for the CMS and ATLAS Phase 2 tracker upgrade. This work has recently led to the development of the RD53B full-scale readout chip which is using the 65nm CMOS process and containing 153600 pixels of 50 × 50 μm$^{2}$ The RD53B chip is designed to be robust against the Single Event Effects (SEE), allowing such a complex chip to operate reliably in the hostile environment of the HL-LHC. Different SEE mitigation techniques based on the Triple Modular Redundancy (TMR) have been adopted for the critical information in the chip. Furthermore, the efficiency of this mitigation scheme has been evaluated for the RD53B chip with heavy ion beams in the CYCLONE facility and with a 480 MeV proton beam in TRIUMF facility. The purpose of this paper is to describe and explain all the SEE mitigation strategies used in the RD53B chip, to report and analyze the heavy ions and proton tests results and to estimate the expected Single Event Upset (SEU) rates at the HL-LHC

The lpGBTIA, a 2.5 Gbps Radiation-Tolerant Optical Receiver using InGaAs photodetector

The Low Power GigaBit Transimpedance Amplifier (lpGBTIA) is the optical receiver amplifier in the lpGBT chipset. It is a highly sensitive transimpedance amplifier designed to operate at 2.56 Gbps. It is implemented in a commercial 65 nm CMOS process. The device has been designed for radiation tolerance and, in particular, to accommodate the radiation effects in photodiodes that manifest themselves as an increase of both their dark current and junction capacitance. The optical receiver consisting of the lpGBTIA connected to an InGaAs photodiode has been successfully tested and irradiation tests showed that the power penalty remains below 4 dBm for exposition to a very high neutron fluences of the order of 10$^{15}$ n/cm$^2$

A Bio-Inspired Analog Silicon Retina with Michaelis-Menten Auto-Adaptive Pixels Sensitive to Small and Large Changes in Light

International audienceIn this paper, we present: (i) a novel analog silicon retina featuring auto-adaptive pixels that obey the Michaelis-Menten law, i.e. $V=V_m I^n/(I^n+\sigma^n)$; (ii) a method of characterizing silicon retinas, which makes it possible to accurately assess the pixels’ response to transient luminous changes in a ±3-decade range, as well as changes in the initial steady-state intensity in a 7-decade Range. The novel pixel, called M2APix, which stands for Michaelis-Menten Auto-Adaptive Pixel, can auto-adapt in a 7-decade range and responds appropriately to step changes up to ±3 decades in size without causing any saturation of the Very Large Scale Integration (VLSI) transistors. Thanks to the intrinsic properties of the Michaelis-Menten equation, the pixel output always remains within a constant limited voltage range. The range of the Analog to Digital Converter (ADC) was therefore adjusted so as to obtain an LSB voltage of 2.35 mV and a full-scale resolution of 9-10 bits. The results presented here show that the M2APix produced a quasi-linear contrast response once it had adapted to the average luminosity. Contrary to what occurs in its biological counterparts, neither the sensitivity to changes in light nor the contrast response of the M2APix depend on the mean luminosity (i.e. the ambient lighting conditions)

Radiation Effects on High-Speed InGaAs Photodiodes

International audiencePhotodiodes are important components in optical data links, and their performance degradation under irradiation has to be understood in order to guarantee the long-term functionality of the data links in radiation environments of high-energy physics experiments. Indium gallium arsenide (InGaAs) on indium phosphide (InP) photodiodes are attractive candidates for these applications, thanks to their relatively modest radiation-induced responsivity loss when operated at 850 nm. In this paper, we present the results that confirm earlier observed additional sensitivity penalties in InGaAs-based receivers. This behavior is further investigated by carrying out several proton tests where InGaAs photodiodes are irradiated together with alternative photodiode types. The critical parameters—responsivity, dark current, and capacitance—are measured up to fluences exceeding ${1\times 10^{16}}$ p/cm2. Radiation-induced dark current is shown to be orders of magnitude higher in InGaAs photodiodes than in GaAs and InGaAs on GaAs photodiodes. However, instead of the dark current increase, the additional losses with InGaAs photodiodes are shown to arise from strongly increased capacitance, which is a dominant feature only in InGaAs photodiodes. This is confirmed with simulations where the measured capacitance characteristics are used in the device model. Our results show that without precautions in the receiver design, radiation-induced capacitance can limit the use of InGaAs photodiodes in harsh radiation environments

Data Transmission System For A High Energy Physics Muon

A data transmission system to be used for a muon detector in a future high energy physics experiment is described, and results are given from beam tests where prototype readout electronics from all the groups involved in the design were tested in a nearly complete chain. The arrangement was very similar to the final system to be built by 2006. Laboratory tests with high speed fibre optic links were also carried out, and preliminary results are presented here