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Assim Boukhayma

Cette personne a quitté l’EPFL

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Publications associées (35)

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A Low-Noise CMOS THz Imager Based on Source Modulation and an In-Pixel High-Q Passive Switched-Capacitor N-Path Filter

Christian Enz, Assim Boukhayma

This paper presents the first low noise complementary metal oxide semiconductor (CMOS) terahertz (THz) imager based on source modulation and in-pixel high-Q filtering. The 31 × 31 focal plane array has been fully integrated in a 0 . 13 μ m standard CMOS pr ...

Mdpi Ag2016

Optimized Detection of Hypoglycemic Glucose Ranges in Human Serum by Raman Spectroscopy with 532 nm Laser Excitation

Christian Enz, Sandro Carrara, Assim Boukhayma, Ata Jedari Golparvar

Raman scattering-based biomedical detection has usually been proposed with near-infrared laser sources. However, a low-cost CMOS imager's quantum efficiency is optimum around green wavelength, and their sensitivity substantially decreases in near-infrared ...

SCITEPRESS2021

Ultra Low Noise CMOS Image Sensors

Assim Boukhayma

CMOS Image Sensors (CIS) overtook the charge coupled devices (CCDs) in low noise performance. Photoelectron counting capability is the next step for CIS for ultimate low light performance and new imaging paradigms. This work presents a review of CMOS image ...

EPFL2016

A Sub-0.5 Electron Read Noise VGA Image Sensor in a Standard CMOS Process

Christian Enz, Assim Boukhayma

A sub-0.5e−rms temporal read noise VGA (640H×480V) CMOS image sensor has been integrated in a standard 0.18μm 4PM CMOS process. The low noise performance is achieved exclusively through circuit optimization without any process refinements. The presented im ...

Ieee-Inst Electrical Electronics Engineers Inc2016

AC/DC Ratio Enhancement in Photoplethysmography Using a Pinned Photodiode

Christian Enz, Assim Boukhayma, Antonino Caizzone

Photoplethysmography (PPG) enables non-invasive vitals monitoring. Nevertheless, it is intrinsically limited by the extremely small AC/DC ratio, also called perfusion-index (PI). This increases the dynamic-range requirements to reliably process the PPG wav ...

Institute of Electrical and Electronics Engineers2019

Compact Modeling of Charge Transfer in Pinned Photodiodes for CMOS Image Sensors

Christian Enz, Farzan Jazaeri, Assim Boukhayma, Raffaele Capoccia

In this paper, we propose a physics-based compact model of the pinned photodiode (PPD) combined with the transfer gate. A set of analytical expressions is derived for the 2-D electrostatic profile, the PPD capacitance, and the charge transfer current. The ...

2019

Time-of-flight device and 3d optical detector

Christian Enz, Assim Boukhayma, Antonino Caizzone

A Time-of-flight optical device and a 3D optical detector comprising a CMOS integrated circuit with an array of photosensitive pixels that are, at least in part, interconnected to form macro-pixels (180). Each macro-pixel (180) groups a plurality of indivi ...

2020

Comparison of Two in Pixel Source Follower Schemes for Deep Subelectron Noise CMOS Image Sensors

Christian Enz, Assim Boukhayma, Antonino Caizzone, Minhao Yang, Daniel Mathias Bold, Andrea Kraxner

This paper compares two in-pixel source follower stage designs for low noise CMOS image sensors embedded both on a same 5 mm by 5 mm chip fabricated in a 180 nm CIS process. The presented chip embeds two pixel variants, one based on a body-effect-canceled ...

IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC2022

An Ultra-Low Power PPG and mm-Resolution ToF PPD-Based CMOS Chip Towards All-in-One Photonic Sensors

Christian Enz, Assim Boukhayma, Antonino Caizzone

This paper presents a CMOS photonic sensor covering multiple applications from ambient light sensing to time resolved photonic sensing. The sensor is made of an array of gated pinned photodiodes (PPDs) averaged using binning and passive switched-capacitor ...

2019

Noise Reduction Techniques and Scaling Effects towards Photon Counting CMOS Image Sensors

Christian Enz, Assim Boukhayma

This paper presents an overview of the read noise in CMOS image sensors (CISs) based on four-transistors (4T) pixels, column-level amplification and correlated multiple sampling. Starting from the input-referred noise analytical formula, process level opti ...

Mdpi Ag2016

Sub-electron CIS noise analysis in 65 nm process

Christian Enz, Assim Boukhayma, Raffaele Capoccia

For a 4T pixel-based CMOS image sensors (CIS) readout chain, with column-level amplification and CDS, we show that the input-referred total noise in a standard 65 nm process can be reduced to 0.37 e-rms. Based on transient noise simulation using Eldo, the ...

2016

Rapid, Sensitive and Selective Optical Glucose Sensing with Stimulated Raman Scattering (SRS)

Christian Enz, Sandro Carrara, Assim Boukhayma, Ata Jedari Golparvar

Optical blood glucose sensing offers pain-free, non-invasive, continuous monitoring with minimum risk of infection since it does not require breaking the skin barrier. Among various optical detection and spectroscopic techniques, only Raman scattering offe ...

IEEE2022

Multispectral image sensor and method for fabrication of an image sensor

Assim Boukhayma

The present invention relates to a multispectral image sensor having a pixel array for detecting images with light components in different wavelength ranges, comprising a plurality of imaging layers each embedded in a semiconductor substrate, wherein in ea ...

2020

A CMOS Image Sensor Pixel Combining Deep Sub-Electron Noise With Wide Dynamic Range

Christian Enz, Assim Boukhayma, Antonino Caizzone

This letter introduces a 5-transistors (5T) implementation of CMOS Image Sensors (CIS) pixels enabling the combination of deep sub-electronnoise performance with wide dynamic range (DR). The 5T pixel presents a new technique to reduce the sense node capaci ...

Institute of Electrical and Electronics Engineers2020

Experimental Verification of the Impact of Analog CMS on CIS Readout Noise

Christian Enz, Assim Boukhayma, Raffaele Capoccia

In this article, the impact of the combination of the column-level gain and the correlated multiple sampling (CMS) on the noise of CMOS image sensor (CIS) readout chains is first analyzed. The theory is then validated experimentally with CIS readout chains ...

2020

Analysis of CMS noise reduction for 65 nm CIS

Christian Enz, Assim Boukhayma, Raffaele Capoccia

This work explores the combination of a downscaled technology with in-pixel source-follower (SF) optimization, a high column-level gain and an analog implementation of Correlated-Multiple-Sampling (CMS) for noise reduction of CIS readout chains. Transient ...

2017

A correlated multiple sampling passive switched capacitor circuit for low light CMOS image sensors

Christian Enz, Assim Boukhayma

After a brief review of the principle of correlated multiple sampling (CMS) and its implementation techniques in CIS readout chains, a simple CMS passive circuit that (i) requires no additional active circuitry, (ii) has no impact on the output dynamic ran ...

IEEE2015

Third-harmonic generation monitoring of femtosecond-laser-induced in-volume functional modifications

Christian Enz, Yves Bellouard, Assim Boukhayma, Olivier Bernard, Andrea Kraxner

During the last two decades, ultrafast in-volume laser-based processing of transparent materials has emerged as a key 3D-printing method for manufacturing a variety of complex integrated photonic devices and micro-parts. Yet, identifying suitable laser pro ...

2023

Pixel sensor cell for cmos image sensors with enhanced conversion gain at high dynamic range capability

Assim Boukhayma

The present invention relates to a pixel sensor cell (1) for a CMOS sensor device comprising: - a photodiode (11) for generating photoelectrons; - a first transfer transistor (12) coupling the photodiode (11) with an intermediate node (IN) and configured t ...

2019

Optical Urea Sensing in Sweat for Kidney Healthcare by Sensitive and Selective Non-enhanced Raman Spectroscopy

Christian Enz, Sandro Carrara, Assim Boukhayma, Ata Jedari Golparvar

Sweat biomarker analysis has attracted much interest in applications ranging from sports to wearable healthcare. Among all the sweat biomolecules, abnormal urea levels have been linked to several complications, particularly renal dysfunction. Here, we repo ...

SPIE-INT SOC OPTICAL ENGINEERING2023