A novel high-frequency interpretation of a general purpose Op-Amp-based negative resistance for chaotic vibrations in a simple a priori nonchaotic circuit

2016 ◽  
Vol 23 (5) ◽  
pp. 744-751 ◽  
Author(s):  
Robert Tchitnga ◽  
Raoul Zebaze Nanfa'a ◽  
François Béceau Pelap ◽  
Patrick Louodop ◽  
Paul Woafo
Keyword(s):  
High Frequency ◽  
A Priori ◽  
Negative Resistance ◽  
General Purpose ◽  
Operational Amplifiers ◽  
Op Amp ◽  
Real Model ◽  
Chaotic Signals ◽  
Theoretical Predictions ◽  
Frequency Interpretation

A novel model of general purpose operational amplifiers is made to approximate, at best, the equivalent circuit for real model at high-frequency. With this new model, it appears that certain oscillators, usually studied under ideal considerations or using many existing real models of operational amplifiers, have hidden subtle and attractive chaotic dynamics that have previously been unknown. These can now be revealed. With the new considerations, a “two-component” circuit, consisting simply of a capacitor in parallel with a nonmodified (and usually presented as a linear, negative) resistance, tends to exhibit chaotic signals. P-Spice and laboratory experimental results are in good agreement with the theoretical predictions.

Improvement of Gain Accuracy and CMRR of Low Power Instrumentation Amplifier Using High Gain Operational Amplifiers

2020 ◽  
Vol 12 (3) ◽  
pp. 168-174
Author(s):  
Rashmi Sahu ◽  
Maitraiyee Konar ◽  
Sudip Kundu
Keyword(s):  
Low Power ◽  
Building Blocks ◽  
High Gain ◽  
The Other ◽  
Operational Amplifiers ◽  
Instrumentation Amplifier ◽  
Biomedical Signals ◽  
Op Amp ◽  
Op Amps ◽  
Multi Stage

Background: Sensing of biomedical signals is crucial for monitoring of various health conditions. These signals have a very low amplitude (in μV) and a small frequency range (<500 Hz). In the presence of various common-mode interferences, biomedical signals are difficult to detect. Instrumentation amplifiers (INAs) are usually preferred to detect these signals due to their high commonmode rejection ratio (CMRR). Gain accuracy and CMRR are two important parameters associated with any INA. This article, therefore, focuses on the improvement of the gain accuracy and CMRR of a low power INA topology. Objective: The objective of this article is to achieve high gain accuracy and CMRR of low power INA by having high gain operational amplifiers (Op-Amps), which are the building blocks of the INAs. Methods: For the implementation of the Op-Amps and the INAs, the Cadence Virtuoso tool was used. All the designs and implementation were realized in 0.18 μm CMOS technology. Results: Three different Op-Amp topologies namely single-stage differential Op-Amp, folded cascode Op-Amp, and multi-stage Op-Amp were implemented. Using these Op-Amp topologies separately, three Op-Amp-based INAs were realized and compared. The INA designed using the high gain multistage Op-Amp topology of low-frequency gain of 123.89 dB achieves a CMRR of 164.1 dB, with the INA’s gain accuracy as good as 99%, which is the best when compared to the other two INAs realized using the other two Op-Amp topologies implemented. Conclusion: Using very high gain Op-Amps as the building blocks of the INA improves the gain accuracy of the INA and enhances the CMRR of the INA. The three Op-Amp-based INA designed with the multi-stage Op-Amps shows state-of-the-art characteristics as its gain accuracy is 99% and CMRR is as high as 164.1 dB. The power consumed by this INA is 29.25 μW by operating on a power supply of ±0.9V. This makes this INA highly suitable for low power measurement applications.

scholarly journals Simulation-Based Power-Loss Optimization of General-Purpose High-Voltage SiC MOSFET Circuit Under High-Frequency Operation

IEEE Access ◽  
2021 ◽  
Vol 9 ◽  
pp. 23786-23794
Author(s):  
Abhishek Kar ◽  
Mitiko Miura-Mattausch ◽  
Mainak Sengupta ◽  
Dondee Navaroo ◽  
Hideyuki Kikuchihara ◽  
...  
Keyword(s):  
High Voltage ◽  
High Frequency ◽  
Power Loss ◽  
General Purpose ◽  
Simulation Based ◽  
High Frequency Operation

A priori assessment of a smart-navigated unmanned aerial vehicle disaster cargo fleet

SIMULATION ◽  
2020 ◽  
Vol 96 (8) ◽  
pp. 641-653
Author(s):  
Jonathan Larson ◽  
Paul Isihara ◽  
Gabriel Flores ◽  
Edwin Townsend ◽  
Danilo R. Diedrichs ◽  
...  
Keyword(s):  
Disaster Response ◽  
Best Practice ◽  
A Priori ◽  
Geographic Distance ◽  
Field Tests ◽  
General Purpose ◽  
Assessment Model ◽  
Sensitivity Analyses ◽  
Modeling And Analysis ◽  
Cargo Delivery

The United Nations Office for the Coordination of Humanitarian Affairs has asserted that risks in deployment of unmanned aerial vehicles (UAVs) within disaster response must be reduced by careful development of best-practice standards before implementing such systems. With recent humanitarian field tests of cargo UAVs as indication that implementation may soon become reality, a priori assessment of a smart-navigated (autonomous) UAV disaster cargo fleet via simulation modeling and analysis is vital to the best-practice development process. Logistical problems with ground transport of relief supplies in Puerto Rico after Hurricane Maria (2017) pose a compelling use scenario for UAV disaster cargo delivery. In this context, we introduce a General Purpose Assessment Model (GPAM) that can estimate the potential effectiveness of a cargo UAV fleet for any given response region. We evaluate this model using the following standards: (i) realistic specifications; (ii) stable output for various realistic specifications; and (iii) support of humanitarian goals. To this end, we discuss data from humanitarian cargo delivery field tests and feedback from practitioners, perform sensitivity analyses, and demonstrate the advantage of using humanitarian rather than geographic distance in making fleet delivery assignments. We conclude with several major challenges faced by those who wish to implement smart-navigated UAV cargo fleets in disaster response, and the need for further GPAM development. This paper proposes the GPAM as a useful simulation tool to encourage and guide steps toward humanitarian use of UAVs for cargo delivery. The model’s flexibility can allow organizations to quickly and effectively determine how best to respond to disasters.

Time-frequency interpretation of ultra-high-frequency QRS components

2014 ◽  
Author(s):  
Pavel Jurak ◽  
Josef Halamek ◽  
Pavel Leinveber ◽  
Tereza Reichlova ◽  
Filip Plesinger ◽  
...  
Keyword(s):  
High Frequency ◽  
Ultra High Frequency ◽  
Time Frequency ◽  
Frequency Interpretation

scholarly journals A Unified Approach to Online Matching with Conflict-Aware Constraints

2019 ◽  
Vol 33 ◽  
pp. 2221-2228
Author(s):  
Pan Xu ◽  
Yexuan Shi ◽  
Hao Cheng ◽  
John Dickerson ◽  
Karthik Abinav Sankararaman ◽  
...  
Keyword(s):  
Online Algorithm ◽  
Broad Class ◽  
A Priori ◽  
Algorithm Design ◽  
Unified Approach ◽  
Bipartite Matching ◽  
Theoretical Predictions ◽  
Online Labor ◽  
Synthetic Datasets ◽  
Event Based

Online bipartite matching and allocation models are widely used to analyze and design markets such as Internet advertising, online labor, and crowdsourcing. Traditionally, vertices on one side of the market are fixed and known a priori, while vertices on the other side arrive online and are matched by a central agent to the offline side. The issue of possible conflicts among offline agents emerges in various real scenarios when we need to match each online agent with a set of offline agents.For example, in event-based social networks (e.g., Meetup), offline events conflict for some users since they will be unable to attend mutually-distant events at proximate times; in advertising markets, two competing firms may prefer not to be shown to one user simultaneously; and in online recommendation systems (e.g., Amazon Books), books of the same type “conflict” with each other in some sense due to the diversity requirement for each online buyer.The conflict nature inherent among certain offline agents raises significant challenges in both modeling and online algorithm design. In this paper, we propose a unifying model, generalizing the conflict models proposed in (She et al., TKDE 2016) and (Chen et al., TKDE 16). Our model can capture not only a broad class of conflict constraints on the offline side (which is even allowed to be sensitive to each online agent), but also allows a general arrival pattern for the online side (which is allowed to change over the online phase). We propose an efficient linear programming (LP) based online algorithm and prove theoretically that it has nearly-optimal online performance. Additionally, we propose two LP-based heuristics and test them against two natural baselines on both real and synthetic datasets. Our LP-based heuristics experimentally dominate the baseline algorithms, aligning with our theoretical predictions and supporting our unified approach.

Quad Band Planar Inverted F Antenna for Smart Phone

2014 ◽  
Vol 573 ◽  
pp. 394-399
Author(s):  
R. Manikandan ◽  
P.K. Jawahar
Keyword(s):  
High Frequency ◽  
Smart Phone ◽  
Analysis And Design ◽  
High Frequency Structure Simulator ◽  
Low Profile ◽  
Resonance Frequencies ◽  
Theoretical Predictions ◽  
Communication Devices ◽  
Device Miniaturization ◽  
Good Agreement

In recent years, the demand for compact handheld communication devices has grown significantly. For device miniaturization antenna size is to be reduced. Micro strip and PIFA have been used for past few years. Since it has low profile geometry it can be embedded into devices. This project is to develop a Quad band small size Planar Inverted F Antenna (PIFA) for the operation in modern multi-band mobile transceiver system. Various techniques for analysis and design of such antenna investigated in this project. The design curve is used to design Quad band Planar inverted F Antenna to operate at the 900, 1800, 2100 and 3500 MHz bands. Since High Frequency Structure Simulator (HFSS) simulation result agrees well with the theoretical predictions, this project also designed through HFSS. An antenna designed at the four desired band and optimized to adjust the four resonance frequencies using HFSS simulation. The substrate FR4 (εr=4.4 & tanδ = 0.02) are in good agreement with the simulation result. Further bandwidth enhancements by making defects in the substrate at particular area were need of much reflection.

A RECORDING SIX‐TRACE CATHODE‐RAY OSCILLOGRAPH

Geophysics ◽  
1947 ◽  
Vol 12 (3) ◽  
pp. 424-431
Author(s):  
Ward Shepard, ◽  
G. L. Beyer,
Keyword(s):  
High Frequency ◽  
High Gain ◽  
General Purpose ◽  
Complete Analysis ◽  
High Input ◽  
High Frequency Response ◽  
Cathode Ray Tubes ◽  
Time Record ◽  
Continuous Displacement ◽  
Excellent Stability

A portable, general purpose six‐trace cathode‐ray oscillograph is described. Eight 2-inch cathode‐ray tubes are arranged side by side in a line. Six of these tubes have individual d.-c. amplifiers with high gain, high input impedance, good high‐frequency response, and excellent stability. The two outside cathode‐ray tubes provide calibrated timing pulses. A removal camera with a fast lens photographs the cathode‐ray tubes on 35-mm. film, to give a continuous displacement‐time record of the cathode‐ray spots. The film may be driven past the lens aperture at speeds continuously variable from a few inches per second to 13 feet per second. A 100-foot film supply system can be used, or a 10-inch strip can be fastened around the drive drum for short records. Film can be processed rapidly, and readily examined with a viewer having a 5 to 10 diameter magnification. More complete analysis of records can be made from enlargements.

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