Mattia Malfatti

A Range Image Sensor Based on 10-

This paper presents the design and characterization of a lock-in pixel array based on a buried channel photo-detector aimed at time-of-flight range imaging. The proposed photo-demodulator has been integrated in a 10-μm pixel pitch with a fill factor of 24%, and is capable of a maximum demodulation frequency of 50 MHz with a contrast of 29.5%. The sensor has been fabricated in a 0.18-μm CMOS imaging technology and assembled in a range camera system setup. The system provides a stream of three-dimensional images at 5-20 fps on a 3-6 m range, with a linearity error lower than 0.7% and a repeatability of 5-16 cm, while the best achievable precision is 2.7 cm at a 50-MHz modulation frequency.

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This paper presents the design and electro-optical test of a 160 × 120-pixels CMOS sensor specifically conceived for Time-Of-Flight 3D imaging. The in-pixel processing allows the implementation of Indirect Time-Of-Flight technique for distance measurement with reset noise removal through Correlated Double Sampling and embedded fixed-pattern noise reduction, whereas a fast readout operation allows the pixels values to be streamed out at a maximum rate of 10 MSample/s. The imager can operate as a fast 2D camera up to 458 fps, as a 3D camera up to 80 fps, or even coupling both operation modes. The chip has been fabricated using a standard 0.18 μm 1P4M 1.8 V CMOS technology with MIM capacitors. The resulting pixel has a pitch of 29.1 μm with a fill-factor of 34% and includes 66 transistors. Distance measurements up to 4.5 m have been performed with pulsed laser light, achieving a best precision of 10 cm at 1 m in real-time at 55 fps and 175 mA current consumption.

Lock-In Pixels in 0.18-

In this paper, an all-analog pixel architecture for the readout of X-ray pixel detectors with multiple energy discrimination is proposed. The circuit comprises a self-triggered reset charge amplifier and three distinct channels devoted to the detection on a specific energy band. Each channel is composed of an autocalibrated comparator, an energy window identification logic, and an analog counter with an adjustable dynamic range. A test prototype has been implemented with a standard complementary metal-oxide-semiconductor 0.35-mum technology. The pixel circuitry dissipates 15 muW at 3.3 V, has a noise equivalent charge of 82 erms - at 200 fF, and allows, on each of the three channels, a dynamic range that exceeds 12 bits. The designed pixel is a square with a 109-mum pitch.

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This paper describes the design and characterization of a 16/spl times/16-pixel image sensor, fabricated in a 0.35 /spl mu/m, 3.3 V CMOS technology for real time three dimensional measurements based on multiple-pulse indirect time-of-flight technique. Owing to an innovative fully differential pixel (FDP) architecture, which allows for the detection of very short and low intensity light pulses, the sensor array provides a range map from 2 m to 9 m with a precision of /spl plusmn/4.0% at 2 m and /spl plusmn/1.7% at 9 m. The pixel power consumption is 100 /spl mu/W, whereas the overall power consumption of the chip is 47 mW in real time operation (30 fps).

m CMOS Imaging Technology

3D vision systems have recently started to penetrate the consumer market, mainly in the entertainment segment, with products based on pattern-projection techniques. Although this technology has shown remarkable performance in terms of cost, measurement accuracy and power consumption, there is also an increasing interest towards alternative techniques, such as stereo vision and Time-of-Flight (ToF), in order to further improve the range camera characteristics. After a decade from the demonstration of the first ToF range imagers with reasonably good performance results [1], this technology has started to attract the attention of large companies, because of the potential consumer applications in security, gaming and ambient assisted living.

A 160

A complete front-end system for resistive gas sensor array is presented. The interface is composed by 8 read-out channels and by 2 closed-loop temperature control circuits. The IC gas sensor read-out structure is based on a controlled oscillator, which acts like a resistance-to-period converter, and achieves a 0.5%-linearity over 500 kOmega-1 GOmega sensor resistance range with a SNR better than 48 dB, corresponding to 114 dB-DR. The temperature control systems allows maintaining a 100degC gradient on the array of sensor, selected in the temperature range 100degC-400degC, with a plusmn2.5degC accuracy. The full device is designed in a standard 0.35 mum CMOS technology. The die area is 1.8 mm2 with a total power consumption of 27 mW from a single 3.3 V supply voltage

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Because we are living in a three-dimensional world, the usual intensity map provided by standard digital cameras is often not sufficient to build the sophisticated models required by systems capable of analyzing and interpreting their environment. A three-dimensional (3D) image sensor has great potential for improvement in many areas like ambient-assisted living, virtual reality, gaming, security and surveillance, etc., because it significantly increases the robustness of object classification and avoids time-consuming post-processing steps. Although the first commercial products are now available on the market, one of the main barriers to mass deployment of such 3D vision tools is the large pixel dimension, which ultimately reduces the sensor resolution and increases costs.

120-Pixels Range Camera With In-Pixel Correlated Double Sampling and Fixed-Pattern Noise Correction

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.

A Multi-Spectral Analog Photon Counting Readout Circuit for X-Ray Hybrid Pixel Detectors

This paper describes the design of a 7times2-pixels array, fabricated in a high voltage 0.35-mum CMOS technology, and specifically conceived for fluorescence lifetime measurements. The incident light is detected using a photodiode biased above its breakdown voltage so that an extremely high sensitivity can be achieved exploiting the intrinsic multiplication effect of the avalanche phenomenon. A single photon avalanche diode combined with an active quenching circuit and a 17-bit digital events counter have been implemented in a 180times150-mum2 pixel. On chip master logic provides the digital control phases required by the pixel array with a fully programmability of the main timing synchronisms. A maximum operating frequency of 40MHz and an observation window within the 0-128ns range with a 0.5ns step are expected

A 16/spl times/16-pixel range-finding CMOS image sensor

The interface IC includes 8 read-out channels and 2 closed-loop temperature control circuits, is fabricated in 0.35mum 2P4M CMOS and dissipates 27mW from a 3.3V supply. The read-out structure, based on a controlled oscillator, achieves a 0.5% linearity and a SNR >48dB over the 500kOmega-1GOmega sensor resistance range with a 114dB DR. The temperature control systems maintain a 100degC gradient in the range 100 to 400degC with plusmn2.5degC accuracy