We present the design and characterization of a large-area, fast-gated, all-digital single-photon detector with programmable active area, internal gate generator, and time-todigital converter (TDC) with a built-in histogram builder circuit, suitable for performing high-sensitivity time-domain nearinfrared spectroscopy (TD-NIRS) measurements when coupled with pulsed laser sources. We used a novel low-power differential sensing technique that optimizes area occupation. The photodetector is a time-gated digital silicon photomultiplier (dSiPM) with an 8.6-mm 2 photosensitive area, 37% fill-factor, and ∼300 ps (20%-80%) gate rising edge, based on low-noise single-photon avalanche diodes (SPADs) and fabricated in 0.35-µm CMOS technology. The built-in TDC with a histogram builder has a least-significant-bit (LSB) of 78 ps and 128 time-bins, and the integrated circuit can be interfaced directly with a low-cost microcontroller with a serial interface for programming and readout. Experimental characterization demonstrated a temporal response as good as 300-ps full-width at half-maximum (FWHM) and a dynamic range >100 dB (thanks to the programmable active area size). This microelectronic detector paves the way for a miniaturized, stand-alone, multi-wavelength TD-NIRS system with an unprecedented level of integration and responsivity, suitable for portable and wearable systems. Index Terms-Digital silicon photomultiplier (dSiPM), fastgated single-photon avalanche diode (SPAD) array, photon counting, time-to-digital converter (TDC), time-domain near-infrared spectroscopy (TD-NIRS). I. INTRODUCTION T IME-DOMAIN near-infrared spectroscopy (TD-NIRS) is a powerful technique for obtaining non-invasive, in vivo measurements of tissue constituents and structure [1]. This can be exploited in many scientific fields, from a clinical Manuscript

Light Detection and Ranging (LiDAR) is a widespread technique for 3D ranging and has widespread use in most automated systems that must interact with the external environment, for instance in industrial and security applications. In this work, we study a novel architecture for Single Photon Avalanche Diode (SPAD) arrays suitable for handheld single point rangefinders, which is aimed at the identification of the objects’ position in the presence of strong ambient background illumination. The system will be developed for an industrial environment, and the array targets a distance range of about 1 m and a precision of few centimeters. Since the laser spot illuminates only a small portion of the array, while all pixels are exposed to background illumination, we propose and validate through Monte Carlo simulations a novel architecture for the identification of the pixels illuminated by the laser spot to perform an adaptive laser spot tracking and a smart sharing of the timing electronics, thus significantly improving the accuracy of the distance measurement. Such a novel architecture represents a robust and effective approach to develop SPAD arrays for industrial applications with extremely high background illumination.

In this work, we present a novel Time-to-Digital Converter (TDC) for single-chip integration in Single-Photon Avalanche-Diode (SPAD) array and digital Silicon Photomultiplier (SiPM). Such novel detector-timing electronics combination will be suitable for Time-Correlated Single-Photon Counting (TCSPC) applications and direct Time-Of-Flight (TOF) measurements. The proposed TDC is based on a 200 MHz 4-bit counter that guarantees a Full-Scale Range of 80 ns. Two interpolators exploit the sliding scale technique to reduce the Differential Non-Linearity (DNL). Besides the coarse interpolation, the multi-stage interpolators have a novel dual-fine interpolation that guarantees a resolution as good as 7 ps, with a conversion time (< 50 ns) much shorter compared to typical architectures based on Vernier delay lines.

No abstract

No abstract