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This article reports the design and characterization of a 32 $\times $ 32 single-photon avalanche diode (SPAD) time-resolved image sensor for quantum imaging applications fabricated in a 150-nm CMOS standard technology. A per-SPAD time-to-digital converter (TDC) records the spatial cross correlation functions of a flux of entangled photons. Each 44.64- $\mu \text{m}$ pixel with 19.48% fill-factor features a 210.2-ps resolution, 50-ns (8-bit) range TDC with 1.28-LSB differential and 1.92-LSB integral nonlinearity (DNL/INL). The sensor achieves an observation rate of up to 1 MHz through a current-based mechanism that avoids reading empty frames when the photon rates are low. A row-skipping mechanism detects the absence of SPAD activity in a row to increase the duty cycle. These two features require only three transistors in each pixel. The sensor functionality is demonstrated in a quantum imaging experiment that achieves super-resolution.

We propose a simulator model to estimate the performance of digital Silicon Photomultipliers (dSiPM) based on Single Photon Avalanche Diodes (SPADs) in terms of detection rate of photons incident on the sensor. The work provides guidelines for efficient array structure depending on: the number of SPADs, fill factor, area of both SPADs and array. A comparison of the main techniques present in the literature to digitally combine multiple outputs into single channel is included with simulated results showing promising higher detection rates for XOR-based dSiPMs. Mathematical expressions are derived to estimate dSiPM parameters such as maximum detection rate and detector dead time as functions of the mentioned design parameters.

We investigate the photon detection efficiency (PDE) and the dynamic range for digital silicon photomultipliers (dSiPMs) over a selection of design parameters: dSiPM unit cell dead time, PDE, unit cell area and fill factor, number of cells, and total dSiPM active area. Two receiver scaling scenarios are considered: varying the number of cells for 1) a fixed unit cell area or 2) a fixed total dSiPM area. Theoretical and simulated results are confirmed with experimental data from a selection of dSiPMs realised on a test chip in $\mathbf {130{\rm{-}nm}}$ CMOS process.

A CMOS single-photon avalanche diode (SPAD)-based quarter video graphics array image sensor with 8- $\mu \text{m}$ pixel pitch and 26.8% fill factor (FF) is presented. The combination of analog pixel electronics and scalable shared-well SPAD devices facilitates high-resolution, high-FF SPAD imaging arrays exhibiting photon shot-noise-limited statistics. The SPAD has 47 counts/s dark count rate at 1.5 V excess bias (EB), 39.5% photon detection probability (PDP) at 480 nm, and a minimum of 1.1 ns dead time at 1 V EB. Analog single-photon counting imaging is demonstrated with maximum 14.2-mV/SPAD event sensitivity and 0.06e− minimum equivalent read noise. Binary quanta image sensor (QIS) 16-kframes/s real-time oversampling is shown, verifying single-photon QIS theory with $4.6\times $ overexposure latitude and 0.168e− read noise.

SPAD-based solid state CMOS image sensors utilising analogue integrators have attained deep sub-electron read noise (DSERN) permitting single photon counting (SPC) imaging. A new method is proposed to determine the read noise in DSERN image sensors by evaluating the peak separation and width (PSW) of single photon peaks in a photon counting histogram (PCH). The technique is used to identify and analyse cumulative noise in analogue integrating SPC SPAD-based pixels. The DSERN of our SPAD image sensor is exploited to confirm recent multi-photon threshold quanta image sensor (QIS) theory. Finally, various single and multiple photon spatio-temporal oversampling techniques are reviewed.

A recently proposed XOR-based digital silicon photomultiplier (dSiPM) is compared against the OR-based counterpart. We show experimental data from a set of single-photon avalanche diode (SPAD) pixel arrays in 130-nm CMOS process with selectable OR tree and XOR tree for direct comparison. We demonstrate how XOR-based dSiPMs solve the limitation caused by monostable circuits and reach higher maximum count rates compared with optimized OR-based dSiPMs. The increased throughput of the SPAD array allows higher sampling rates for the digitization of the light signal enhancing dynamic range and linearity.