An 11-bit 2MS/s column parallel SAR-RAMP ADC for ToF imager readout

Time-of-Flight (ToF) is an optical range detection technique that derives range from the round-trip time of light pulse between the imager and the target. Due to the simple hardware and distance extraction algorithm, ToF imagers are widely adopted in existing (automotive, consumer electronics, etc.) and emerging (AR/VR, etc.) applications...

CMOS SPAD Sensors for 3D Time-of-Flight Imaging, LiDAR and Ultra-High Speed Cameras

In conventional applications, such as bio-imaging and microscopy, SPAD is typically used as a single-photon counter. However, this advantage has been challenged by other photon-counting technologies, especially from CMOS-based QIS. Comparatively, apart from single-photon counting capability, QIS is superior to SPAD in terms of intrinsic multi...

A CMOS SPAD Imager with Collision Detection and 128 Dynamically Reallocating TDCs for Single-Photon Counting and 3D Time-of-Flight Imaging

Per-pixel time-to-digital converter (TDC) architectures have been exploited by single-photon avalanche diode (SPAD) sensors to achieve high photon throughput, but at the expense of fill factor, pixel pitch and readout efficiency. In contrast, TDC sharing architecture usually features high fill factor at small pixel pitch and energy efficient...

High-Performance Back-Illuminated Three-Dimensional Stacked Single-Photon Avalanche Diode Implemented in 45-nm CMOS Technology

We present a high-performance back-illuminated three-dimensional stacked single-photon avalanche diode (SPAD), which is implemented in 45-nm CMOS technology for the first time. The SPAD is based on a P⁺/Deep N-well junction with a circular shape, for which N-well is intentionally excluded to achieve a wide depletion region, thus...

Single-grain Si thin-film transistors for monolithic 3D-ICs and flexible electronics

We review our recent achievements in monolithic 3D-ICs and flexible electronics based on single-grain Si TFTs that are fabricated inside a single-grain with a low-temperature process. Based on pulsed-laser crystallization and submicron sized cavities made in the substrate, amorphous-Si precursor film was converted into poly-Si having grains that...

Toward one giga frames per second: Evolution of in Situ storage image sensors

The ISIS is an ultra-fast image sensor with in-pixel storage. The evolution of the ISIS in the past and in the near future is reviewed and forecasted. To cover the storage area with a light shield, the conventional frontside illuminated ISIS has a limited fill factor. To achieve higher sensitivity, a BSI ISIS was developed. To avoid direct...

Data Acquisition System Design for a 160x128 Single-photon Image Sensor with On-pixel 55 ps Time-to-digital Converter

Time-resolved image sensors enabling picosecond resolutions over large formats are needed in many advanced imaging fields, from fluorescence lifetime imaging microscopy (FLIM) to positron emission tomography (PET). Integrated single-photon avalanche diode (SPAD) technology embodies the new frontiers of time-resolved imaging, namely better...

An insect eye based image sensor with very large field of view

In this paper we discuss the design of a novel miniaturized image sensor based on the working principle of insect facet eyes. The main goals are to design an imaging system which captures a large field of view (FOV) and to find a good trade-off between image resolution and sensitivity. To capture a total FOV of 124°, we split up this FOV into 25...