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Over the past few years there has been a growing interest in monolithic arrays of single photon avalanche diodes (SPADs) for parallel detection of faint ultrafast optical signals. SPADs implemented in CMOS-compatible planar technologies offer the typical advantages of microelectronic devices (small size, ruggedness, low voltage, low power, etc.). Furthermore, they have inherently higher photon detection efficiency than photomultiplier tubes and they are able to provide very high acquisition speeds. The development of fully-parallel multichannel systems is a challenge both for the detector (with new problems like optical and electrical crosstalk, isolation elements size reduction and the need for higher yields) and for the electronics. The development of a parallel detector must be accompanied by that of the time-to-amplitude converters and analysis electronics necessary in time-correlated single photon counting applications. In this paper we present the fundamental building blocks necessary to develop a parallel picosecond array detector: a new high-performance SPAD detector, compatible with the design of multi-detector systems with a large number of channels, and a new totally integrated system for time-to-amplitude conversion, to allow the simple integration of several channels on a single chip. [ABSTRACT FROM AUTHOR]

This paper investigates the application of a mixed-signal synchronous/asynchronous digital controller to dc-dc boost converters. The digital control synchronously generates current and voltage ramps by using two low-resolution digital-to-analog converters. The switch turn-on and turn-off are determined asynchronously by comparing the converter-state variables and the digitally generated current and voltage ramps. The control features high dynamic performance, frequency modulation during transients, small quantization effects, and low complexity. In order to evaluate the dynamic performance and compare the proposed solution with conventional analog peak-current-mode control, a small-signal model of the synchronous/asynchronous modulation is derived. Even if aimed to an integrated digital controller, experimental investigation has been performed by using discrete components, implementing the digital control in a field-programmable gate array by using a VHDL. The simulation and experimental results on 100-W dc-dc boost converter confirm the proposed analysis and show that the proposed solution enables a dynamic performance that is comparable with that of analog peak-current-mode control. [ABSTRACT FROM AUTHOR]

This paper investigates power line communication (PLC) in digitally controlled high-frequency switched-mode power supplies in distributed architectures that share the same bus voltage. Communication between different dc-dc converters is obtained by using switching frequency modulation and by detecting the switching signal on the common supply bus voltage. In case of low power transmission, a small duty-cycle perturbation at half of switching frequency is added to enhance the energy of the transmitted signal. Each converter operates at three different switching frequencies: the first is associated with bit 1 transmission, the second is associated with bit 0 transmission, and the third is associated with no transmission state. In the proposed solution, there is no need for an additional power amplifier in order to inject the communication signal on the power lines, but the signal used for the PLC is inherently generated by the pulsewidth modulation of dc-dc converters. Even if aimed at a dedicated digital IC, the communication architecture has been implemented in field- programmable gate arrays. Simulation and experimental results on dc-dc synchronous buck converters confirm that the performance is achievable by the proposed PLC techniques. [ABSTRACT FROM AUTHOR]

Design and fabrication of single photon avalanche detector (SPAD) in planar technology is reported. Device design and critical issues in the technology are discussed. Experimental test procedures are described for dark-counting rate, afterpulsing probability, photon timing resolution, and quantum detection efficiency. Low-noise detectors are obtained, with dark counting rates down to 10 c/s for devices with 10 µm diameter, down to 1 kc/s for 50 µm diameter. The technology is suitable for monolithic integration of SPAD detectors and associated circuits. [ABSTRACT FROM AUTHOR]

Focuses on the monolithic dual-detector for photon-correlation spectroscopy with wide dynamic range and 70-ps resolution. Use of semiconductor photodiodes in detecting single photons; Autocorrelation function of light pulse; Time-resolution of detector instruments.

Introduces the first integrated active quenching circuit (I-AQC) that drives an avalanche photodiode above its breakdown voltage in order to detect single photons. Why the duration of single-photon avalanche diode avalanche current must be as short as possible; Components of the I-AQC; Design guidelines of the I-AQC; Description of the detection module; Experimental results.

Presents a study which manufactured high-sensitivity solid-state detectors designed for measurements in laser scanning microscopy. Discussion on laser scanning microscopy; Description of photodetectors structures; Results and discussion; Conclusions.