An Ultracompact 9.4–14.8-GHz Transformer-Based Fractional-N All-Digital PLL in 40-nm CMOS

In this paper, we apply various area reduction techniques on an inductor–capacitor (LC)-tank oscillator in order to make its size comparable to that of ring oscillators (ROs), while still retaining its salient features of excellent phase noise and low sensitivity to supply variations. The resulting oscillator employs a proposed ultracompact...

Mutually Coupled Time-to-Digital Converters (TDCs) for Direct Time-of-Flight (dTOF) Image Sensors

Direct time-of-flight (dTOF) image sensors require accurate and robust timing references for precise depth calculation. On-chip timing references are well-known and understood, but for imaging systems where several thousands of pixels require seamless references, area and power consumption limit the use of more traditional synthesizers, such as...

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...

Modular time-of-flight image sensor for light detection and ranging: A digital approach to LIDAR

Constant increase in data processing efficiency has enabled, among many other things, the intensive use of depth mapping technologies. Consumer applications, such as gaming, augmented and virtual realities (AR/VR), and other human-machine interfaces, are typically based on intensive image processing, either by triangulation and/or structured...