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Bedrich Hosticka - IEEE Xplore Author Profile

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Single-Photon Avalanche Diode (SPAD)-based 'Light Detection And Ranging' (LiDAR) systems often use the first photon measurement principle to acquire ranging information. While those systems provide accurate distance measurements, they can easily saturate in high background scenarios. Recent improvements in SPAD quenching circuit technology open up the opportunity for SPAD LiDAR systems to detect m...Show More
Indirect time-of-flight (TOF) measurement with single-photon avalanche diodes (SPADs) is performed by counting incident photons in several time windows. Since SPADs exhibit dead time not all incident photons can be counted within a given time window. This affects the expected values and, hence, the variance of the distance measurement. For photon detection rates close to the inverse of the dead ti...Show More
We present a 1×80 pixel line sensor for direct time-of-flight measurement based on single-photon avalanche diodes fabricated in a high-voltage 0.35 pm CMOS process. An in-pixel time-to-digital-converter with a resolution of 312.5 ps determines the arrival time of the first-photon for each emitted laser pulse from a flash illumination source for all pixels in parallel. Distance determination is per...Show More
For applications like autonomous driving a fast and reliable monitoring of the vehicle's environment is essential. With the possibility of fabricating single-photon avalanche diodes in standard CMOS processes, small and cost-efficient time-of-flight sensors can be realized. To estimate the performance of such a sensor a general theoretical model taking into account the properties of the light sour...Show More
This communication addresses the range accuracy of SPAD-based time-of-flight (TOF) sensors that employ laser pulse modulation. Two basic approaches are considered: indirect and direct TOF. We investigate confidence intervals and derive formulas for standard errors of the relative distance error for both approaches based on photon statistics.Show More
Indirect time-of-flight measurement with SPADs is performed by counting incident photons in several time windows. Since SPADs exhibit dead time not all incident photons can be counted within a given time window. This affects the expected values and, hence, the variance of the distance measurement. For photon detection rates close to the inverse of the dead time, which defines the maximum count rat...Show More
High ambient illumination reduces the range and target detection reliability in light-based 3D sensors. Raising the optical power of the artificial illumination source to overcome the influence of high ambient light is often not possible for systems with flash illumination due to eye safety constraints. The high timing resolution of single-photon avalanche diodes enables the search for photon conc...Show More
With the possibility of fabricating single-photon avalanche diodes in standard CMOS processes, arrays for range imaging applications have been developed. Proper operation in high ambient illumination environments is one of the major issues of scannerless sensors published so far. In this paper a theoretical study of the direct and indirect working principle regarding high ambient illumination is s...Show More
In recent years, various developments have advanced the field of optical sensors based on single-photon avalanche diodes. In this contribution we present two sensors that were designed in 0.35μm CMOS technology. A silicon photomultiplier achieves a fill factor of 68 % at 50 μm pixel pitch and allows improved functionality by cointegration of application-specific readout electronics. A time-gated l...Show More
A novel architecture for a bandgap voltage reference is presented in this paper. The voltage reference, designed for image sensor applications, is primarily targeted for a low-noise operation along with other practical constraints such as high power supply rejection, temperature immunity and short start-up time. The analysis and operation of the circuit is discussed and the trade-offs involved in ...Show More
Recently a 128×96 pixel range imager with a pitch of 40 μm and a fill factor of 38 % was presented for 3D range imaging measurements based on the pulse modulated (PM) time-of-flight (ToF) principle. This sensor employs a high-speed photodetector called lateral drift-field photodiode (LDPD). During the characterization insufficiencies in charge transfer were observed for low-light illumination. Her...Show More
In this work an ultra-thin bendable imaging test structure is presented and experimental results are put forward. The deployed design and layout rules in order to achieve an independent operation on the applied mechanical stress are discussed. Moreover, experimental results of the optical characteristics of standard n+/p photodiodes on ultra-thin silicon chips embedded into a polyimide foil under ...Show More
In this paper, theoretical as well as experimental results of the investigations on a bendable ultrathin Si monolithic CMOS image sensor are presented. The electro-optical behavior of a thinned flexible CMOS active pixel sensor for the application of uniaxial mechanical stress is theoretically and experimentally analyzed. The necessity of a correlated double sampling readout scheme to achieve a st...Show More
The authors report on a novel linear time-invariant (LTI) modeling of a flow sensor system based on thermal Time-of-Flight (TOF) principle by using pulsed hot wire anemometry. Thermal heat pulses are electrically generated at the hot wire centered in a pipe, carried along by the fluid in flow direction, and detected at several positions downstream. The flow sensor consisting of a hot wire and seve...Show More
Performing digital signal processing in continuous time can be advantageous for a number of applications like biomedical implants, hearing aids, remote sensors, telecommunications, audio and speech processing. While the inherent advantages of digital implementations with respect to programmability and noise immunity are retained by this kind of signal processing, the power consumption can be much ...Show More
Design and measurement results of a CMOS 128 × 96 pixel sensor are presented, which can be used for three-dimensional (3D) scene reconstruction applications based on indirect time-of-flight (ToF) principle enabled by pulse modulated active laser illumination. The 40μm pitch pixels are based on the novel intrinsic lateral drift-field photodiode (LDPD) that allows for a 30ns complete charge transfer...Show More
The use of continuous-time domain or frequency domain analysis in switched-capacitor systems may often be formally inapplicable due to insufficient mathematical conditions based on the system operating properties itself. This paper introduces a switching time-frequency domain method for the estimation of noise in such systems, while there is no need for periodicity. The switching domain method req...Show More
This article describes a pulsed thermal Time-of-Flight (TTOF) flow sensor system as two subsystems i.e., a pulsed-wire system and a heat flow system. The entire flow sensor is regarded system-theoretically as a linear time-invariant (LTI) system and is described by its transfer function or impulse response. The characterization of the thermo-fluid dynamic signals obtained by a pulsed-wire and by a...Show More
Scannerless 3D-Time-of-Flight image sensors serve to acquire three-dimensional (3D) information of objects in a scene. This contribution is devoted to modeling and calibration of scannerless 3D-Time-of-Flight image sensors based on pulse modulation. After a short description we introduce a 3D image sensor model that includes system nonlinearities due to nonideal photodetectors and signal processin...Show More
A system-theoretical model of an air flow sensor based on the principle of pulsed thermal Time-of-Flight (TTOF) is described. The region of interest (ROI) in the pipe flow is regarded as a linear time-invariant (LTI) system with an input and output signal. Based on the experimental results the simulation model is created and applied for analysis of different input signals and system's responses wi...Show More
Systems which perform digital signal processing in continuous-time are attractive for a number of applications like biomedical implants, hearing aids, remote sensors, telecommunications, and audio and speech processing. A main difference to sampled data systems is the realization of the delay elements which must be implemented as quasi-continuous time delay lines. Thus a large chip area is require...Show More
Thermal flow measurement is currently based on the principle of heat energy displacement caused by a flowing fluid (mass flow measurement). The heat is induced by a continuous heating element immersed into the fluid. This kind of sensor is only applicable for fluids with known homogeneity properties. The presented investigation is based on a discontinuous heating element using the pulsed Thermal T...Show More
A novel CMOS pixel architecture is presented, which fulfills the need for acquisition of very high photon fluxes at high temperatures. A buried photodiode based pixel structure was analysed in detail, and then applied to fabricate the 256 × 256 large area imager sensor in a standard 0.5μm CMOS process using mask reticle stitching.Show More
A novel photodetector concept for high charge transfer speed and low image lag is presented. The key feature of the so-called Lateral Drift-Field Photodetector (LDPD) is a lateral electric drift field inside the photoactive area of the device. This results in a significant acceleration of the charge collection compared to conventional diffusion based detectors and, therefore, this device is an ide...Show More
A novel time-of-flight (ToF) 3D-image sensor based on photogate (PG) active pixel structures fabricated in a standard 0.35 mum CMOS process is presented. Distance measurements are performed using a pulsed near-infrared (lambda = 905 nm) laser with pulse widths of 30 ns to 60 ns for distance measurements up to 9 m. The developed ToF pixel consists of a photogate (APG = 30 x 30 mum2) and four floati...Show More