Tatiana Danov

A comprehensive CMOS APS crosstalk study: photoresponse model, technology, and design trends

In this paper the lateral photoresponse and crosstalk (CTK) in complementary metal-oxide-semiconductor (CMOS) photodiodes is investigated by means of a unique sub-micron scanning system (S-cube system) and numerical device simulation. An improved semi-analytical model developed for photoresponse estimation of a photodiode-based CMOS active pixel sensor reveals the photosignal and the CTK dependence on the pixels geometrical shape and arrangement within the array. The trends that promise to increase CMOS image sensor performance are presented and design tradeoffs intended to optimize the photoresponse and minimize CTK are discussed.

Theoretical approach to CMOS APS PSF and MTF modeling - evaluation

In this work, a fully theoretical CMOS active pixel sensor (APS) modulation transfer function model is formulated, evaluated, and compared with practical results. The model is based on a two-dimensional diffusion equation solution and covers the symmetrical photocarriers diffusion effect together with the impact of the pixel active area geometrical shape. Thorough scanning results obtained by means of a unique submicron scanning system (the S-cube system) from various APS chips, implemented in a standard CMOS 0.35-/spl mu/m technology, are compared with our theoretical predictions. The agreement of the presented comparison results indicates that for any potential active area shape, an analytical reliable estimate of image performance is possible.

Spectral Analysis of Relativistic Dyadic Green's Function of a Moving Dielectric-Magnetic Medium

The present contribution is concerned with obtaining plane-wave spectral representations of the relativistic electric and magnetic dyadic Greens functions of an isotropic dielectric-magnetic medium (at the frame-at-rest) that is moving in a uniform velocity. By applying a simple coordinate transformation, scalarization of the EM vectorial problem is obtained in which the EM dyads are evaluated from Helmholtzs isotropic scalar Greens function. The spectral plane-wave representations of the dyadic Greens functions are obtained by applying the spatial 2D Fourier transform to the scalar Greens function. We investigate these spectral representations in the under and over phase-speed regimes, as well as 2D and 3D formulations and discuss the associated wave phenomena.

A Simple and Direct Time Domain Derivation of the Dyadic Green's Function for a Uniformly Moving Non-Dispersive Dielectric-Magnetic Medium

The present contribution is concerned with deriving the relativistic electric and magnetic time-dependent dyadic Greens functions of an isotropic dielectric-magnetic medium (at the frame-at-rest) that is moving in a uniform relativistic velocity under the framework of the Minkowski constitutive relations. The results presented here correct previous reports in the literature [R. Compton, J. Math. Phys. 7, 2145 (1966)] and [C. Tai, J. Math. Phys. 8, 646 (1967)]. By applying a simple space-time and fields-sources transformation, scalarization of the vectorial problem is obtained. Thus the electromagnetic dyads are evaluated from the Greens function of the scalar (time-dependent) wave equation in free space. Emphasis is placed on a simple and direct time domain derivation.

Study of CMOS APS responsivity enhancement: ring-shaped photodiode

In this brief, the possibilities of complementary metal-oxide-semiconductor (CMOS) active pixel sensor (APS) spectral response improvement are discussed. Thorough submicrometer scanning results obtained from various ring-shaped pixel photodiodes with different inner radius, implemented in a standard CMOS 0.35-/spl mu/m technology, are compared with numerical computer simulations and verified analytically. The functional dependence of the pixel response on the ring opening size was discovered and formulated for various wavelengths illumination. We show that the photodiodes with a small ring-opening exhibit better sensitivity in the blue spectrum range (420-460 nm). Comparison between the simulation and measurement results shows a good agreement, hence, proving that specific photodiode designs enable to selectively improve pixel color sensitivity.

Point-by-point thorough photoresponse analysis of CMOS APS by means of our unique submicron scanning system

This work shows the progress and demonstrates the measurements performed via a unique submicron scanning system developed at the VLSI systems center in Ben-Gurion University. The system enables the combination of near-field optical and atomic force microscopy measurements with the standard electronic analysis. The obtained signal, i.e., the electrical outcome at each point as a function of the spot position provides a 2D signal map of the pixel response, representing the full 3D charge distribution in the device. This work present the results obtained by thorough scanning of several various pixel topologies of CMOS APS chips fabricated in two different CMOS technologies (the standard 0.5μm and 0.35μm CMOS technologies). We demonstrate that our system use enables a detailed, point by point, quantitative determination of the contributions to the total output signal from each particular region of the pixel. It makes possible to understand the influence of the each component composing the pixel (e.g., logic transistors, metal lines, etc.) which is extremely important for CMOS APS where the pixel structure defines a fill factor of less then 100%.

Two-dimensional relativistic longitudinal Green’s function in the presence of a moving planar dielectric–magnetic discontinuity

The current contribution is concerned with obtaining the relativistic two-dimensional (three-dimensional in relativity jargon) Greens function of a time-harmonic line current that is embedded in a moving dielectric-magnetic medium with a planar discontinuity. By applying a plane-wave (PW) spectral representation for the relativistic electromagnetic Greens function of a dielectric-magnetic medium that is moving in a uniform velocity, the exact reflected and transmitted (refracted) fields are obtained in the form of a spectral integral over PWs in the so-called laboratory and comoving frames. We investigate these spectral representations, as well as their asymptotic evaluations, and discuss the associated relativistic wave phenomena of direct reflected/transmitted rays and relativistic head waves (lateral waves).

STT Analysis of the Time-Dependent Reflected Field From a Moving Dielectric–Magnetic Planar Discontinuity

This paper is concerned with obtaining closed-form exact solution for the 2-D canonical problem of the reflected field from a moving planar discontinuity of a dielectric–magnetic medium that is excited by an impulsive line current. The spectral theory of transient (STT) that originally deals with nondispersive frequency-domain plane-wave spectra is used in this paper for addressing a time-variant scattering problem. The scattering from a moving object yields dispersive and anisotropic PW spectra. Nevertheless, we demonstrate that the STT is capable of dealing with these types of spectra and obtain the desired exact time-dependent solutions. The unique wave phenomena that are associated with the medium and scatterer velocity are explored.

Time-dependent plane wave spectral analysis of the dyadic Green’s function of a fast moving dielectric-magnetic medium

Abstract We investigate the plane wave spectral representations of the time-dependent relativistic electric and magnetic dyadic Green’s functions (GFs) of an isotropic dielectric-magnetic medium that is moving in a constant velocity. We distinguish two speed regimes in which the medium is moving slower or faster than its wave speed. Using a scalarization process for the EM vectorial problem, the EM dyads are evaluated from scalar GF. The spectral plane wave representations of the dyadic GFss are obtained using the those of the scalar ones according to the appropriate speed regime. We investigate the resulting spectral representations and the associated wave phenomena. Such spectral representations are essentials for solving different canonical scattering problems in which the sources are decomposed into time-dependent (transient) plane waves as part of the boundary problem solutions.

Relativistic current line Green's function in the presence of a moving planar dielectric-magnetic medium

The present contribution is concerned with obtaining the relativistic 2D (3D in relativity jargon) Greens function of a time-harmonic line current that is embedded in a moving dielectric-magnetic medium with a planar discontinuity. By applying a plane-wave spectral representation for the relativistic electromagnetic Greens function of a dielectric-magnetic medium that is moving in a uniform velocity, the exact incident and reflected fields are obtained in the form of a spectral integral over plane-waves in the so-called comoving frames. We investigate these spectral representations as well as their asymptotic evaluations and discuss the associated relativistic wave phenomena of direct reflected rays and relativistic head-waves.