Telescopic Op-Amp Optimization for MDAC Circuit Design

An 8-bit 40-MS/s low power Multiplying Digital-to-Analog Converter (MDAC) for a pipelined-to-Analog to Digital converter (ADC) is presented. The conventional dedicated operational amplifier (Op-Amp) is performed by using telescopic architecture that features low power and less-area. Further reduction of power and area is achieved by using multifunction 1.5bit/stage MDAC architecture. The design of the Op-Amp is performed by the elaboration of a program based on multi objective genetic algorithms to allow automated optimization. The proposed program is used to find the optimal transistors sizes (length and width) in order to obtain the best Op-Amp performances for the MDAC. In this study, six performances are considered, direct current gain, unity-gain bandwidth, phase margin, power consumption, area, slew rate, thermal noise, and signal to noise ratio. The Matlab optimization toolbox is used to implement the program. Simulations were performed by using Cadence Virtuoso Spectre circuit simulator in standard AMS 0.18μm CMOS technology. A good agreement is observed between the results obtained by the program optimization and simulation, after that the Op-Amp is introduced in the MDAC circuit to extract its performances

Comparative study of various methods for extraction of multi quantum wells Schottky diode parameters

In this work, forward current voltage characteristics for multi-quantum wells Al0.33Ga0.67As Schottky diode were measured at temperature ranges from 100 to 300 K. The main parameters of this Schottky diode, such as the ideality factor, barrier height, series resistance and saturation current, have been extracted using both analytical and heuristics methods. Differential evolution (DE), particle swarm optimization (PSO) and artificial bee colony (ABC) have been chosen as candidate heuristics algorithms, while Cheung technic was selected as analytical extraction method. The obtained results show clearly the high performance of DE algorithms in terms of parameters accuracy, convergence speed and robustness

Artificial bee colony algorithm: a novel strategy for optical constants and thin film thickness extraction using only optical transmittance spectra for photovoltaic applications

An effective approach to determine thin film thickness (d) and optical constants (n, k, α) from transmittance spectrum with interference fringes is proposed. The developed strategy is based on applying the artificial bee colony (ABC) algorithm and Cauchy dispersion model. The accuracy test of this method has been assessed by using simulated and real tests. Simulated test is used to check the ability of ABC algorithm to determine the parameters of simulated transmittance spectra. Real test deals with the investigation of the determination approach on experimental measured transmittance spectra. Those spectra were measured from six elaborated samples of amorphous hydrogenated silicon (a-Si:H) thin films with different thicknesses, which will be used as an eco-friendly layer for solar cell applications. The obtained results noticeably show the high effectiveness of the developed strategy to accurately determine the thin film thickness and optical constants

Investigation of the effects of thermal annealing on the structural, morphological and optical properties of nanostructured Mn doped ZnO thin films

The control of the optical properties of ZnO nanostructured thin films by using different dopant elements paves the way for the development of potential materials for photonic and optoelectronic applications. In this work manganese (Mn) doped ZnO thin films were fabricated by rapid thermal evaporation method on a glass substrate having the same Mn content level of ~10% and annealed at different temperatures. XRD analysis showed that the annealed layers have hexagonal wurtzite structure, however, the unannealed layers showed only Zn peaks without any preferential direction. The elemental analysis of the films has been investigated by XPS, which revealed the presence of Mn and oxygen atoms for all layers. In addition, it was observed by FIB-SEM that the morphology of thin films changed with the annealing temperature. For an anneal at 500 °C nanoneedles appeared. Raman spectroscopy showed E1 (TO) mode in the sample annealed at 500 °C which was attributed with the formation of nanoneedles structures. The optical transmission of the annealed films was in the range of 75–77% and the optical bandgap varied from 3.97 to 3.72 eV. These variations are related to the structural and morphological changes of the thin films with annealing temperature

Comparison of electrical performances of two n-in-p detectors with different implant type of guard ring by TCAD simulation

This paper presents a preliminary comparative study for two different guard rings structures in the purpose of evaluating their electrical performances. The two structures are based on the n-in-p technology with different implant type of guard rings. I–V characteristics have been simulated using Silvaco/ATLAS software for both structures and compared for various parameters of substrate, guard ring and oxide. Simulation results show that the shape of leakage current is almost the same in all simulations but in terms of breakdown voltage, n-in-p structure with n-type guard rings ensures high voltage stability. Keywords: Breakdown voltage, Guard ring, n-in-p silicon detector, TCAD simulatio

Characterization and simulation of radiation effects on active edges n-on-p technology planar pixel sensors

International audienceThe ATLAS inner tracker has to be upgraded to meet the requirements for radiation hardness and geometrical acceptance in order to withstand the harsh conditions of High Luminosity LHC (HL-LHC). This requires segmented silicon sensors of increased geometrical efficiency. The active edge technology allows to reduce the inactive area at the border of the sensor. The main objective of this work is to evaluate by TCAD simulation, conducted using Silvaco™ TCAD software, the performance of planar n-on-p technology sensors with active edges exposed to high level of radiation for fluences up to 1×1016neq/cm2, using a three-level trap model for ptype FZ silicon material. By using the secondary ion mass spectrometry (SIMS) technique, an accurate representation of the sensor structure was obtained in terms of doping concentration profile. Charge collection efficiency (CCE) is studied as a function of radiation fluence. •Secondary Ion Mass Spectrometry method (SIMS) is used to investigate the doping profile.•The charge collection efficiency (CCE) are simulated a function of radiation fluence.•An ADVACaM edgless sensor matrix is implemented in a full TCAD simulation

Performance of n-on-p planar pixel sensors with active edges at high-luminosity environment

International audienceFuture high-energy physics experiments require highly segmented silicon sensors of increased geometrical efficiency with the ability to withstand extremely high radiation damage. The performance of planar n-on-p sensors with active edges is simulated at high radiation fluences up to 1 × 10$^{16}$ n$_{eq}$/cm$^{2}$, using a three-level trap model for p-type silicon material. Taking advantage of the secondary ion mass spectrometry (SIMS) technique, an accurate representation of the structure was obtained in terms of doping profile. The breakdown voltage, leakage current, hole density and electric field distributions as well as the charge collection efficiency (CCE) are studied as a function of radiation fluence