Publications by Preethi Padmanabhan

A 256x128 3D-Stacked (45nm) SPAD FLASH LiDAR with 7-Level Coincidence Detection and Progressive Gating for 100m Range and 10klux Background Light

Edoardo Charbon, Chunmin Zhang, Preethi Padmanabhan, Myung Jae Lee, Baris Can Efe, Augusto Ronchini Ximenes

IEEE2021

Direct time-of-flight SPAD image sensors for light detection and ranging

Depth sensing is an increasingly important feature in many applications of consumer, automotive, augmented/virtual reality (AR-VR), space and bio-medical imaging. Long range, high depth resolution, high spatial resolution, and high frame rates are often co ...

EPFL2021

Direct time-of-flight depth sensor architecture and method for operating of such a sensor

Edoardo Charbon, Preethi Padmanabhan

The present invention relates to a direct time-of-flight depth imaging sensor comprising: an array of photodetectors (43) arranged in one or more subgroups (41), wherein each subgroup (41) is divided into a plurality of minigroups (42) of photodetectors (4 ...

2020

Photon detecting 3d imaging sensor device

Edoardo Charbon, Preethi Padmanabhan, Augusto Ronchini Ximenes

The invention relates to a photon detecting 3D imaging sensor device for detecting a distance information for pixels in an image, comprising: - an array of detector units, wherein each detector unit is configured to receive a light signal pulse and to prov ...

2019

Modeling and Analysis of a Direct Time-of-Flight Sensor Architecture for LiDAR Applications

Edoardo Charbon, Chunmin Zhang, Preethi Padmanabhan

Direct time-of-flight (DTOF) is a prominent depth sensing method in light detection and ranging (LiDAR) applications. Single-photon avalanche diode (SPAD) arrays integrated in DTOF sensors have demonstrated excellent ranging and 3D imaging capabilities, ma ...

2019

A Modular, Direct Time-of-Flight Depth Sensor in 45/65-nm 3-D-Stacked CMOS Technology

Edoardo Charbon, Preethi Padmanabhan, Myung Jae Lee, Augusto Ronchini Ximenes

This article introduces a modular, direct time-of-flight (TOF) depth sensor. Each module is digitally synthesized and features a 2

\times

(8

\times

8) single-photon avalanche diode (SPAD) pixel array, an edge-sensitive decision tree, a shared time-to ...

2019

Oscillator arrangement for time-to-digital converter for large array of time-of-flight image sensor devices

Edoardo Charbon, Preethi Padmanabhan, Augusto Ronchini Ximenes

An oscillator arrangement for time-to-digital converters for a 3D image sensor device includes a plurality of oscillators arranged as an array each oscillator being associated to one time-to-digital converter, and at least one coupling unit respectively ar ...

2019

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

Edoardo Charbon, Preethi Padmanabhan, Myung Jae Lee, Augusto Ronchini Ximenes

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 whi ...

2018

A back-illuminated 3D-stacked single-photon avalanche diode in 45nm CMOS technology

Edoardo Charbon, Preethi Padmanabhan, Myung Jae Lee, Augusto Ronchini Ximenes

We report on the world's first back-illuminated 3D-stacked single-photon avalanche diode (SPAD) in 45nm CMOS technology. This SPAD achieves a dark count rate of 55.4cps/μm 2 , a maximum photon detection probability of 31.8% at 600nm, over 5% in the 420-920 ...

2018

A 256x256 45/65nm 3D-Stacked SPAD-Based Direct TOF Image Sensor for LiDAR Applications with Optical Polar Modulation for up to 18.6dB Interference Suppression

Edoardo Charbon, Preethi Padmanabhan, Myung Jae Lee, Augusto Ronchini Ximenes

Light detection and ranging (LiDAR) systems based on direct time-of-flight (DTOF) are used in spacecraft navigation, assembly-line robotics, augmented and virtual reality (AR/VR), (drone-based) surveillance, advanced driver assistance systems (ADAS), and a ...

IEEE2018

A Hybrid Readout Solution for GaN-Based Detectors Using CMOS Technology

Edoardo Charbon, Preethi Padmanabhan

2018

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

Edoardo Charbon, Preethi Padmanabhan, Augusto Ronchini Ximenes

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 refe ...

2018

A CMOS Front-end for GaN-based UV Imaging

Edoardo Charbon, Preethi Padmanabhan

2017

Single Photon Counting UV Solar-Blind Detectors Using Silicon and III-Nitride Materials

Edoardo Charbon, Preethi Padmanabhan

Ultraviolet (UV) studies in astronomy, cosmology, planetary studies, biological and medical applications often require precision detection of faint objects and in many cases require photon-counting detection. We present an overview of two approaches for ac ...

2016