Fast Sensing and Quenching of CMOS SPADs for Minimal Afterpulsing Effects

We present a single-photon avalanche diode (SPAD) front-end circuitry, in a cost-effective 0.35 μm CMOS technology, for single-photon detection in the visible wavelength range, aimed at speeding up the sensing of detector ignition and at promptly quenching the avalanche current buildup. The circuit allows the reduction in detrimental effects of afterpulsing through reducing any delays in the electronics intervention on the detector and through a proper time-varying action of the MOS transistors on the different SPAD’s operating conditions. The sensing time is reduced down to a few hundreds of picoseconds, with an active quenching transition of about 1 ns for 6 V excess bias, and a final reset in just 3 n

Large-area CMOS SPADs with very low dark counting rate

We designed and characterized Silicon Single-Photon Avalanche Diodes (SPADs) fabricated in a high-voltage 0.35 μm CMOS technology, achieving state-of-the-art low Dark Counting Rate (DCR), very large diameter, and extended Photon Detection Efficiency (PDE) in the Near Ultraviolet. So far, different groups fabricated CMOS SPADs in scaled technologies, but with many drawbacks in active area dimensions (just a few micrometers), excess bias (just few Volts), DCR (many hundreds of counts per second, cps, for small 10 μm devices) and PDE (just few tens % in the visible range). The novel CMOS SPAD structures with 50 μm, 100 μm, 200 μm and 500 μm diameters can be operated at room temperature and show DCR of 100 cps, 2 kcps, 20 kcps and 100 kcps, respectively, even when operated at 6 V excess bias. Thanks to the excellent performances, these large CMOS SPADs are exploitable in monolithic SPAD-based arrays with on-chip CMOS electronics, e.g. for time-resolved spectrometers with no need of microlenses (thanks to high fillfactor). Instead the smaller CMOS SPADs, e.g. the 10 μm devices with just 3 cps at room temperature and 6 V excess bias, are the viable candidates for dense 2D CMOS SPAD imagers and 3D Time-of-Flight ranging chips

Large-area CMOS SPADs with very low dark counting rate

We designed and characterized Silicon Single-Photon Avalanche Diodes (SPADs) fabricated in a high-voltage 0.35 µm CMOS technology, achieving state-of-the-art low Dark Counting Rate (DCR), very large diameter, and extended Photon Detection Efficiency (PDE) in the Near Ultraviolet. So far, different groups fabricated CMOS SPADs in scaled technologies, but with many drawbacks in active area dimensions (just a few micrometers), excess bias (just few Volts), DCR (many hundreds of counts per second, cps, for small 10 µm devices) and PDE (just few tens % in the visible range). The novel CMOS SPAD structures with 50 mm, 100 µm, 200 µm and 500 µm diameters can be operated at room temperature and show DCR of 100 cps, 2 kcps, 20 kcps and 100 kcps, respectively, even when operated at 6 V excess bias. Thanks to the excellent performances, these large CMOS SPADs are exploitable in monolithic SPAD-based arrays with on-chip CMOS electronics, e.g. for time-resolved spectrometers with no need of microlenses (thanks to high fillfactor). Instead the smaller CMOS SPADs, e.g. the 10 µm devices with just 3 cps at room temperature and 6 V excess bias, are the viable candidates for dense 2D CMOS SPAD imagers and 3D Time-of-Flight ranging chips

Monolithic time-to-digital converter chips for time-correlated single-photon counting and fluorescence lifetime measurements

We present a low-power Time-to-Digital Converter (TDC) chip, fabricated in a standard cost-effective 0.35 μm CMOS technology, which provides 160 ns dynamic range, 10 ps timing resolution and Differential Non-Linearity better than 0.01 LSB rms. This chip is the core of a compact TDC module equipped with an USB 2.0 interface for user-friendly control and data-acquisition. The TDC module is suitable for a wide variety of applications such as Fluorescence Lifetime Imaging (FLIM), time-resolved spectroscopy, Diffuse Optical Spectroscopy (DOS), Optical Time-Domain Reflectometry (OTDR), quantum optics, etc. In particular, we show the application of our TDC module to fluorescence lifetime measurements

A compact Time-to-Digital Converter (TDC) Module with 10 ps resolution and less than 1.5% LSB DNL

We present a low-power Time-to-Digital Converter (TDC) module that provides 10 ps timing resolution, DNL better than 1.5% LSB and 160 ns dynamic range within a compact 6 cm x 6 cm x 8 cm housing. The USB link to the remote PC allows the easy setting of measurement parameters, the fast download of acquired data, and their visualization and storing via an userfriendly software interface. The module is suitable for a wide variety of applications such as: FLIM, FRET, TOF ranging measurements, TOF PET, DOT, OTDR, quantum optics, etc

3D Sensor for indirect ranging with pulsed laser source

The growing interest for fast, compact and cost-effective 3D ranging imagers for automotive applications has prompted to explore many different techniques for 3D imaging and to develop new system for this propose. CMOS imagers that exploit phase-resolved techniques provide accurate 3D ranging with no complex optics and are rugged and costeffective. Phase-resolved techniques indirectly measure the round-trip return of the light emitted by a laser and backscattered from a distant target, computing the phase delay between the modulated light and the detected signal. Singlephoton detectors, with their high sensitivity, allow to actively illuminate the scene with a low power excitation (less than 10W with diffused daylight illumination). We report on a 4x4 array of CMOS SPAD (Single Photon Avalanche Diodes) designed in a high-voltage 0.35 μm CMOS technology, for pulsed modulation, in which each pixel computes the phase difference between the laser and the reflected pulse. Each pixel comprises a high-performance 30 μm diameter SPAD, an analog quenching circuit, two 9 bit up-down counters and memories to store data during the readout. The first counter counts the photons detected by the SPAD in a time window synchronous with the laser pulse and integrates the whole echoed signal. The second counter accumulates the number of photon detected in a window shifted with respect to the laser pulse, and acquires only a portion of the reflected signal. The array is readout with a global shutter architecture, using a 100 MHz clock; the maximal frame rate is 3 Mframe/s

Safety of anti-tumour necrosis factor agents in patients with chronic hepatitis C infection: a systematic review

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