The large interest shown in the field of terahertz detectors research by the scientific community brought to the
development of several kinds of devices based on different principles. Many, however, have some peculiar
characteristics that prevent their use in low-cost or compact equipment, because of cryogenic cooling, or the use of
exotic materials, etc.
Recently, approaches using field-effect transistors exploiting the oscillation of electron density (plasma waves) or the
phenomena known as "self-mixing" in RF modulators, allowed to foresee the possibility to employ standard CMOS
technologies to build such sensors.
In this work we analyze the behavior of this kind of detectors in order to understand how to design an optimized device
and then how to exploit it by proper readout. Optimized electromagnetic coupling to the detector has been implemented
using a dipole antenna. Electromagnetic simulations together with the developed model allowed calculating a projected
noise figure of the detector of 38ρW / √Hz. Two dedicated readout circuits have been designed, one intended to read the
detector as a current generator, while the other reads it as a voltage generator. The developed circuits have been designed
and sent for fabrication in a standard 0.35μm CMOS technology.
In this paper a Time-Of-Flight range camera based on Current Assisted Photonic Demodulators is presented. The sensor,
fabricated in a 0.18 μm CMOS technology, features 120x160 pixel resolution with 10μm pixel pitch and 24% fill factor.
Pixel, camera and system architectures are described highlighting the most important design issues, and a selection of
experimental results is presented. The chip has a power consumption of 200mW, mainly due to the contribution of
modulation current. A range camera system was realized using the proposed sensor, a focusing optics providing a
23°x30° field of view, and a 3-LED illumination module delivering 140mW optical power on the target. The system is
capable of acquiring a stream of 7 3D frames/s with a maximum non-linearity of 3.3% in the range 1.2m-3.7m and a
precision better than 10 cm at 2m and 20 cm at 3m.
Fluorescence lifetime detection is widely used in molecular biology to monitor many cell parameters (such as pH, ion
concentrations, etc.) and for an early diagnosis of many pathologies. In a typical fluorescence lifetime experiment a
pulsed laser is used to excite the fluorescent dyes and the emitted light is revealed by means of high sensitivity detectors,
typically: intensified CCD, PMTs or Single-Photon Avalanche Diodes (SPADs).In this contribute we present a SPAD
detector module fabricated in a 0.35μm High Voltage CMOS technology to be used within a lab-on-chip system
consisting of a micro-reactor array for bioaffinity assays based on fluorescence markers. The detector module, having a
total area of 600 x 900 μm2, can be arranged to build a small pixel array to be directly coupled to the micro-reactors. No
emission filters are needed, since the ultra-short laser pulse is cut off in the time domain. The module consists of a
10x10-SPAD array, where each SPAD cell is equipped with dedicated active quenching and recharging circuit. Each cell
has a pitch of 26μm with a fill factor of 48%. The SPADs have been binned in order to realize a large photosensitive area
detector exhibiting a reasonably low dark count rate (DCR) and reduced dead time, as required in a fast measurement
system. A memory has also been implemented in order to enable only low DCR SPADs, so that a total DCR of about
100kHz can be achieved for the whole photosensitive area. The digital output generated by the SPAD array is sent to a
time-discriminator stage which allows a time-gated detection of the incident light. Two time-windows have been
implemented in this architecture. Their time width is controlled by an on-chip digital PLL locked to the external laser
clock whereas the width of the time-windows can be set within the range 500ps-10ns with a resolution of 500ps. Photons
detected within each time window are then counted by two 10-bits digital counters. Time-interleaved operation has been
implemented to read out the pixel data in parallel with the photon detection phase.
The digital documentation of monuments and architectures is an important field of application of the 3D modeling where
both visual quality and precise 3D measurement are important. This paper proposes an integrated approach based upon
the combination of different 3D modeling techniques for the virtual reconstruction of complex architectures like those
found in medieval castles. The need of combining multiple techniques, like terrestrial laser scanning, photogrammetry
and digital surveying comes from the complexity of some structures and by the lack of a single technique capable of
giving satisfactory results in all measuring conditions. This paper will address modeling issues related to the automation
of photogrammetric methods and to the fusion of 3D models acquired with different techniques, at different point
densities and measurement accuracies. The test bench is a medieval castle placed in Trentino A.A., a tiny region in
A fast, low power CMOS sensor for optical tracking is presented. The tracking function is carried out by pointing at the target with a collimated light beam and estimating the position of the back-reflected beam portion impinging on the device. An example of optical tracking sensor is represented by a Position Sensitive Detector (PSD). This work presents a novel architecture of a 2D pixel array for single spot detection and tracking, based on image outline extraction. The prototype device, designed in standard 0.8 μm CMOS technology, consists of an array of 20x20 pixels with a pitch of 70.25 μm and a fill factor of 12%. The photosensitive detector is provided with analogue processing circuitry and digital blocks which allow to extract the spot centroid. Two different multiple threshold working modes are adopted in order to improve the sensor accuracy and frame rate. The light spot position can be estimated in 120 μsec with an accuracy of 0.9 μm, when the sensor is operated with the first mode. The second mode is adopted to improve the frame rate. The chip exhibits a worst case power cosumption of 15 mW @ 5 V and a frame rate up to 3000 frames/s.
This paper reports on the development of an intelligent electro-optical device for the 3D detection of drive scenarios and obstacles recognition; the work is being carried out in the frame of a national program, under the acronym OPTO3D and involving Centro Ricerche Fiat, Istituto per la Ricerca Scientifica e Tecnologica and University of Trento. The system is finalized to automotive drive assistance functions, particularly to the pre-crash application. It is based on a new CMOS image sensor that enhances the passive 2D vision through the on-pixel integration of distance information, with high dynamic range. The 3D detection is based on a novel active imaging technique, derived from the time of flight concept. Novel intelligent processing algorithms support the objects recognition.
This paper presents a comparative analysis of different analog-to-digital conversion architectures optimized for operation in close coupling with optical sensor arrays in the presence of stringent design constraints such as signal and noise levels, conversion rates and physical size of the array. Architectures based on a single converter per array and on multiple converters per array are considered. Measurement results on dedicated converters integrated in experimental chips together with optical arrays have proved the validity of the architectures presented, with different trade-off points in term of power consumption, conversion rate and spatial uniformity.