A Range Image Sensor Based on 10-$\mu{\hbox {m}}$ Lock-In Pixels in 0.18-$\mu$m CMOS Imaging Technology

Stoppa, David; Massari, Nicola; Pancheri, Lucio; Malfatti, M.; Perenzoni, Matteo; Gonzo, L.

doi:10.1109/jssc.2010.2085870

Cited by 94 publications

(45 citation statements)

References 15 publications

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“…The techniques used to implement I-TOF cameras differ from the light modulation point of view, with continuous wave (CW) modulation or pulsed light, but also from the device implementation, from a conventional photodiode with complex processing electronics [2,3], to CCD-like photodiode for electrical demodulation [4], photogate structures on CMOS field-oxide [5], ohmic junctions for minority carriers demixing [6], single-photon avalanche diodes in integrating (counting) operation [7] and buried channel photodemodulator [8].…”

Section: Open Accessmentioning

confidence: 99%

“…Moreover, the illuminator power is pulsed and accumulated N times in a frame, with a requirement of minimum duty-cycle given by the laser specifications: therefore, the number of accumulations is the equivalent of the exposure time and determines also the 3D frame rate which can be achieved with this sensor. Table 1 summarizes the main parameters which can be used to analytically calculate some of the presented figures of merit using Equations (7) and (8). The calculations, for the different frame rate values, give a PR corr from 20.1 to 39.5 V/(W/m 2 ) and a NED from 1.2 and 3.3 cm/√Hz, whereas the measurements give PR corr from 16.7 to 31.3 V/(W/m 2 ) and a NED from 1.4 to 3.4 cm/√Hz.…”

Section: Evaluation Of 3d Sensor Based On Pulsed Techniquementioning

confidence: 99%

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Figures of Merit for Indirect Time-of-Flight 3D Cameras: Definition and Experimental Evaluation

Perenzoni

Stoppa

2011

Remote Sensing

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Indirect Time-of-Flight (I-TOF) cameras can be implemented in a number of ways, each with specific characteristics and performances. In this paper a comprehensive analysis of the implementation possibilities is developed in order to model the main performances with a high level of abstraction. After the extraction of the main characteristics for the high-level model, several figures of merit (FoM) are defined with the purpose of obtaining a common metric: noise equivalent distance, correlated and uncorrelated power responsivity, and background light rejection ratio. The obtained FoMs can be employed for the comparison of different implementations of range cameras based on the I-TOF method: specifically, they are applied for several different sensors developed by the authors in order to compare their performances.

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Section: Open Accessmentioning

confidence: 99%

Section: Evaluation Of 3d Sensor Based On Pulsed Techniquementioning

confidence: 99%

Figures of Merit for Indirect Time-of-Flight 3D Cameras: Definition and Experimental Evaluation

Perenzoni

Stoppa

2011

Remote Sensing

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“…Time-resolved (TR) CMOS imagers have recently been paid much attention in applications of time-of-flight range imaging [1,2,3,4], biological imaging [5,6,7], and so on. A state-of-the-art TOF range imager [4] has demonstrated the high range resolution of 0.3 mm, which corresponds to time resolution of 2 ps.…”

Section: Introductionmentioning

confidence: 99%

A column-parallel clock skew self-calibration circuit for time-resolved CMOS image sensors

Miao

Yasutomi

Imanishi³

et al. 2015

IEICE Electron. Express

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This letter reports a column-parallel clock skew self-calibration circuit for time-resolved (TR) CMOS image sensors. In TR CMOS imagers, as the time resolution increases, the skew of gating clock between pixels becomes a difficult problem because the clock skew causes the reduction of measurable maximum range in particular pixels or unmeasurable pixels. To calibrate the skew in short time, a column-parallel skew self-calibration circuit based on two-stage delay line and a dual clock tree is proposed. The experimental results show that the skew calibration circuit successfully reduces the skew from 247 ps rms to 25 ps rms , and the calibration time is only 12 µs, which is much faster than the previous work.

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“…Column signal lines are separate for color and range pixels. ADC and ToF signal processing is performed off-chip.Each Z pixel is a pinned photodiode with two transfer gates and two output ports [4,5]. For ranging, the scene is illuminated with 850nm NIR LEDs modulated at 20MHz.…”

mentioning

confidence: 99%

“…Each Z pixel is a pinned photodiode with two transfer gates and two output ports [4,5]. For ranging, the scene is illuminated with 850nm NIR LEDs modulated at 20MHz.…”

mentioning

confidence: 99%

A 1.5Mpixel RGBZ CMOS image sensor for simultaneous color and range image capture

Kim

Wang

Ovsiannikov

et al. 2012

2012 IEEE International Solid-State Circuits Conference

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A 1.5Mpixel RGBZ image sensor that simultaneously captures color (RGB) and time-of-flight (ToF) range (Z) images is presented. While ToF sensors are well documented [1,2], few, if any, monolithic sensors have been reported that capture both range and color. In one sensor [3], a combined pixel structure captures color and range, but presumably in sequential fields. This approach does not allow simultaneous capturing of range with color, and the pixel performance cannot be optimized for each mode. In thie paper, we introduce a sensor that is designed to capture color and range simultaneously with individually optimized pixels.It is expected that future mobile-phone cameras and compact DSCs will be able to capture 3D still and video images, and permit gesture control of certain functions. ToF range sensing has several advantages over stereo-imaging or motioncomputed 3D imaging, including single-lens implementation, less-intensive computing requirements, and freedom from occlusion artifacts. Monolithic integration of color and ToF range sensing for a single-lens camera system is important for those consumer applications that require small-form-factor cameras with lowest-possible cost.In our sensor, color (RGB) and range (Z) pixels are tiled across the image plane. Our RGBZ sensor is modified from a 1920(H)×1080(V) 2Mpixel array of standard 2.5T pixel RGBG color pixels with 2.25µm pitch. Every 3 rd row of color pixels is replaced with a row of Z pixels. Each Z pixel is 2.25×9.0µm2 . Thus the RGBZ kernel consists of two RGBG color kernels and one Z pixel. There are, in essence, two interlaced arrays: a 1920(H)×720(V) physical array of color pixels with an embedded 480(H)×360(V) array of range pixels for a total of 1.55Mpixels. A block diagram of the experimental sensor is shown in Fig. 22.7.1. The color pixels are driven from the left and read out at the top of the array. Range pixels are driven from the right and read out at the bottom. Column signal lines are separate for color and range pixels. ADC and ToF signal processing is performed off-chip.Each Z pixel is a pinned photodiode with two transfer gates and two output ports [4,5]. For ranging, the scene is illuminated with 850nm NIR LEDs modulated at 20MHz. The two transfer gates TG1 and TG2 in the Z pixel are modulated 180°o ut of phase with each other at 20MHz. On one phase the optical signal is integrated on a floating diffusion (FD), and on the other phase the signal is discarded using a drain diffusion (DD). This single-tap mode of operation requires four fields to be collected, corresponding to the four quadrature phases. Each phase field is integrated and then read out. The LED modulation phase is shifted for each field. Our single-tap operation eases layout design and reduces fixed-pattern noise compared to traditional two-tap operation, but SNR is reduced by a factor of √2.Organization of the sensor into range-pixel "stripes" allows for easier routing of modulation-control lines to the range pixels and leads to less high-frequencyclock contamination of th...

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A Range Image Sensor Based on 10-$\mu{\hbox {m}}$ Lock-In Pixels in 0.18-$\mu$m CMOS Imaging Technology

Cited by 94 publications

References 15 publications

Figures of Merit for Indirect Time-of-Flight 3D Cameras: Definition and Experimental Evaluation

Figures of Merit for Indirect Time-of-Flight 3D Cameras: Definition and Experimental Evaluation

A column-parallel clock skew self-calibration circuit for time-resolved CMOS image sensors

A 1.5Mpixel RGBZ CMOS image sensor for simultaneous color and range image capture

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