scholarly journals Classification and Design Space Exploration of Low-Power Three-Stage Operational Transconductance Amplifier Architectures for Wide Load Ranges

Electronics ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 1268 ◽  
Author(s):  
Joseph Riad ◽  
Johan J. Estrada-López ◽  
Edgar Sánchez-Sinencio
Keyword(s):  
Figure Of Merit ◽  
Design Space Exploration ◽  
Building Blocks ◽  
Operational Transconductance Amplifiers ◽  
The Past ◽  
Transconductance Amplifier ◽  
Transconductance Amplifiers ◽  
Analog Systems ◽  
The Stability ◽  
Selection Of

Since operational transconductance amplifiers (OTAs) form the basic building blocks of many analog systems, the compensation of three-stage OTAs has attracted a lot of attention in the literature. Many different solutions to the stability problem of such OTAs have been proposed over the past 20 years, with each solution exhibiting different properties or targeting a different application. This work surveys a broad selection of previously reported architectures and proposes a novel classification scheme that exposes features common to seemingly different compensation architectures and serves as a guideline for which type of OTA is suitable for a given application. In addition, a novel figure of merit (FoM) is proposed to guide the designer in deciding which OTA architecture suits the tradeoffs specific to the application at hand. Theoretical discussions are further reinforced by transistor-level simulation results.

Design and Comparative Analysis of High Performance Carbon Nanotube-Based Operational Transconductance Amplifiers

NANO ◽  
2015 ◽  
Vol 10 (03) ◽  
pp. 1550039 ◽  
Author(s):  
Sajad A. Loan ◽  
M. Nizamuddin ◽  
Abdul R. Alamoud ◽  
Shuja A. Abbasi
Keyword(s):  
Comparative Analysis ◽  
Carbon Nanotube ◽  
High Performance ◽  
Output Resistance ◽  
Operational Transconductance Amplifiers ◽  
Rejection Ratio ◽  
Power Supply Rejection Ratio ◽  
Key Characteristics ◽  
Transconductance Amplifiers ◽  
The Stability

In this paper, novel carbon nanotube (CNT) based operational transconductance amplifiers (OTAs) have been designed and simulated. Three types of CNT-based OTAs have been designed at 45 nm technology node and have been compared with the conventional CMOS-based OTA. The comparative analysis of the key characteristics of all the devices has revealed that a significant improvement in performance is observed in the CNT-based OTAs, particularly in a pure CNT-OTA. In the pure CNT-OTA, DC gain has increased by 218%, slew rate has increased by 22.58%, the output resistance has increased by 55.2% and the power consumption is ∼ 193 times less in comparison to the conventional CMOS-OTA. Further, common mode rejection ratio (CMRR) and power supply rejection ratio positive (PSRR+) has increased by 31.87% and 136.3%, respectively in pure CNT-OTA. The performance of CNT-based OTAs has also been studied thoroughly by varying the number of CNTs (N), CNT pitch (S) and the diameter of CNTs (D CNT ) at 0.9 V. It has been observed that their performance can be improved further by using optimized values of CNT number; inter CNT-pitch and diameter. The stability analysis has shown that the pure CNT-OTA is highly stable. A 16.7% and 4% increase in phase and gain margins is achieved in the pure CNT-OTA in comparison to the bulk CMOS OTA. Finally, band and high pass filters have been realized by using the proposed CNT-based OTAs.

scholarly journals Tetrathiafulvalene – a redox-switchable building block to control motion in mechanically interlocked molecules

2018 ◽  
Vol 14 ◽  
pp. 2163-2185 ◽  
Author(s):  
Hendrik V Schröder ◽  
Christoph A Schalley
Keyword(s):  
Molecular Motion ◽  
Functional Unit ◽  
Molecular Machines ◽  
Building Blocks ◽  
Interlocked Molecules ◽  
The Past ◽  
Research Challenge ◽  
And Control ◽  
Redox Switches ◽  
Selection Of

With the rise of artificial molecular machines, control of motion on the nanoscale has become a major contemporary research challenge. Tetrathiafulvalenes (TTFs) are one of the most versatile and widely used molecular redox switches to generate and control molecular motion. TTF can easily be implemented as functional unit into molecular and supramolecular structures and can be reversibly oxidized to a stable radical cation or dication. For over 20 years, TTFs have been key building blocks for the construction of redox-switchable mechanically interlocked molecules (MIMs) and their electrochemical operation has been thoroughly investigated. In this review, we provide an introduction into the field of TTF-based MIMs and their applications. A brief historical overview and a selection of important examples from the past until now are given. Furthermore, we will highlight our latest research on TTF-based rotaxanes.

scholarly journals A State of Art Survey for OS Performance Improvement

2018 ◽  
Vol 6 (3) ◽  
pp. 118-123 ◽  
Author(s):  
Lailan M. Haji ◽  
Subhi R.M. Zeebaree ◽  
Karwan Jacksi ◽  
Diyar Q. Zeebaree
Keyword(s):  
Performance Improvement ◽  
Critical Issue ◽  
The Past ◽  
Performance Requirements ◽  
And Performance ◽  
Measurement And Evaluation ◽  
The Stability ◽  
High Level ◽  
Multiple Metrics ◽  
Selection Of

Through the huge growth of heavy computing applications which require a high level of performance, it is observed that the interest of monitoring operating system performance has also demanded to be grown widely. In the past several years since OS performance has become a critical issue, many research studies have been produced to investigate and evaluate the stability status of OSs performance. This paper presents a survey of the most important and state of the art approaches and models to be used for performance measurement and evaluation. Furthermore, the research marks the capabilities of the performance-improvement of different operating systems using multiple metrics. The selection of metrics which will be used for monitoring the performance depends on monitoring goals and performance requirements. Many previous works related to this subject have been addressed, explained in details, and compared to highlight the top important features that will very beneficial to be depended for the best approach selection.

scholarly journals Grounded Capacitor Oscillators Using A Single Operational Transconductance Amplifier

1996 ◽  
Vol 19 (2) ◽  
pp. 91-98 ◽  
Author(s):  
Muhammad Taher Abuelma'atti ◽  
Muhammad Haroon Khan
Keyword(s):  
Frequency Dependence ◽  
Operational Transconductance Amplifier ◽  
Independent Control ◽  
Operational Transconductance Amplifiers ◽  
Transconductance Amplifier ◽  
Transconductance Amplifiers ◽  
Oscillator Circuits

New oscillator circuits using operational transconductance amplifiers (OTAs) are presented. Each circuit uses a single OTA and grounded capacitors. The feasibility of obtaining oscillators with independent control of frequency and oscillation is considered. Also, the feasibility of exploiting, to advantage, the frequency dependence of the OTA-transconductance is considered. This may result in OTA-based RC oscillators using only one externally-connected capacitor.

Integrated FAHP-VIKOR model for green supplier selection in a Nickle coating SME

2020 ◽  
pp. 133-139
Author(s):  
Sanatan Ratna ◽  
B Kumar
Keyword(s):  
Staff Training ◽  
Supplier Selection ◽  
Fuzzy Ahp ◽  
Research Work ◽  
Supplier Evaluation ◽  
Green Supplier Selection ◽  
The Past ◽  
Coating Industry ◽  
Sustainability Issue ◽  
Selection Of

In the past few decades, there has been lot of focus on the issue of sustainability. This has occurred due to the growing concerns related to climate change and the growing awareness about environmental concerns. Also, the competition at global level has led to the search for the most sustainable route in the industries. The current research work deals with the selection of green supplier in a Nickle coating industry based on certain weighted green attributes. For this purpose, a hybrid tool comprising of Fuzzy AHP (Fuzzy Analytical Hierarchy) and VIKOR (VlseKriterijumska Optimizacija I Kompromisno Resenje) is used. The Fuzzy AHP is used for assigning proper weights to the selected criteria for supplier evaluation, while VIKOR is used for final supplier selection based on the weighted criteria. The three criterions for green supplier selection are, Ecological packaging, Corporate socio-environmental responsibility and Staff Training. The outcome of the integrated model may serve as a steppingstone to other SMEs in different sectors for selecting the most suitable supplier for addressing the sustainability issue.

Stability and Folding of the Unusually Stable Hemoglobin from Synechocystis is Subtly Optimized and Dependent on the Key Heme Pocket Residues.

2020 ◽  
Vol 27 ◽  
Author(s):  
Sheetal Uppal ◽  
Mohd. Asim Khan ◽  
Suman Kundu
Keyword(s):  
Molten Globule ◽  
Life Forms ◽  
Model System ◽  
Heme Pocket ◽  
The Past ◽  
Specific Manner ◽  
Delivery Vehicles ◽  
The Stability ◽  
Key Residues ◽  
Synechocystis Sp

Aims: The aim of our study is to understand the biophysical traits that govern the stability and folding of Synechocystis hemoglobin, a unique cyanobacterial globin that displays unusual traits not observed in any of the other globins discovered so far. Background: For the past few decades, classical hemoglobins such as vertebrate hemoglobin and myoglobin have been extensively studied to unravel the stability and folding mechanisms of hemoglobins. However, the expanding wealth of hemoglobins identified in all life forms with novel properties, like heme coordination chemistry and globin fold, have added complexity and challenges to the understanding of hemoglobin stability, which has not been adequately addressed. Here, we explored the unique truncated and hexacoordinate hemoglobin from the freshwater cyanobacterium Synechocystis sp. PCC 6803 known as “Synechocystis hemoglobin (SynHb)”. The “three histidines” linkages to heme are novel to this cyanobacterial hemoglobin. Objective: Mutational studies were employed to decipher the residues within the heme pocket that dictate the stability and folding of SynHb. Methods: Site-directed mutants of SynHb were generated and analyzed using a repertoire of spectroscopic and calorimetric tools. Result: The results revealed that the heme was stably associated to the protein under all denaturing conditions with His117 playing the anchoring role. The studies also highlighted the possibility of existence of a “molten globule” like intermediate at acidic pH in this exceptionally thermostable globin. His117 and other key residues in the heme pocket play an indispensable role in imparting significant polypeptide stability. Conclusion: Synechocystis hemoglobin presents an important model system for investigations of protein folding and stability in general. The heme pocket residues influenced the folding and stability of SynHb in a very subtle and specific manner and may have been optimized to make this Hb the most stable known as of date. Other: The knowledge gained hereby about the influence of heme pocket amino acid side chains on stability and expression is currently being utilized to improve the stability of recombinant human Hbs for efficient use as oxygen delivery vehicles.

Formation of Carbon-Oxygen Bond Mediated by Hypervalent Iodine Reagents Under Metal-free Conditions

2020 ◽  
Vol 17 ◽  
Author(s):  
Ayesha Jalil ◽  
Yaxin O Yang ◽  
Zhendong Chen ◽  
Rongxuan Jia ◽  
Tianhao Bi ◽  
...  
Keyword(s):  
Natural Products ◽  
Bond Formation ◽  
Building Blocks ◽  
Review Article ◽  
Hypervalent Iodine ◽  
Metal Free ◽  
Bioactive Natural Products ◽  
The Past ◽  
Oxygen Bond ◽  
Privileged Scaffolds

: Hypervalent iodine reagents are a class of non-metallic oxidants have been widely used in the construction of several sorts of bond formations. This surging interest in hypervalent iodine reagents is essentially due to their very useful oxidizing properties, combined with their benign environmental character and commercial availability from the past few decades ago. Furthermore, these hypervalent iodine reagents have been used in the construction of many significant building blocks and privileged scaffolds of bioactive natural products. The purpose of writing this review article is to explore all the transformations in which carbon-oxygen bond formation occurred by using hypervalent iodine reagents under metal-free conditions

Evidence-based Assessment

2010 ◽  
pp. 76-98
Author(s):  
John Hunsley ◽  
Eric J. Mash
Keyword(s):  
Decision Making ◽  
Clinical Assessment ◽  
Assessment Process ◽  
Evidence Based ◽  
The Past ◽  
Specific Assessment ◽  
The Many ◽  
Selection Of ◽  
Made In

Evidence-based assessment relies on research and theory to inform the selection of constructs to be assessed for a specific assessment purpose, the methods and measures to be used in the assessment, and the manner in which the assessment process unfolds. An evidence-based approach to clinical assessment necessitates the recognition that, even when evidence-based instruments are used, the assessment process is a decision-making task in which hypotheses must be iteratively formulated and tested. In this chapter, we review (a) the progress that has been made in developing an evidence-based approach to clinical assessment in the past decade and (b) the many challenges that lie ahead if clinical assessment is to be truly evidence-based.

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