Modeling of hot-carrier degradation of p-MOSFET?s

Bu çalışmanın amacı, sıcak taşıyıcılar nedeniyle p-MOSFET’lerde oluşan parametre yorulmaların analog uygulamalara uygun modellenmesidir. Tümdevre elemanların çalışmaları süresince sıcak taşıyıcıların neden olduğu elektronların tuzaklara yakalanma ve/veya tuzaklar oluşturma ve/veya yüzey tuzaklar oluşturması sonucunda oksit yükü ve tuzak yoğunluğu değişmektedir. Bu güne kadar sıcak taşıyıcıların oluşumu ve modellenmesi üzerinde çok sayıda çalışma bulunmaktadır. Fakat, bu araştırmaların tamamına yakını sayısal uygulamalar, için yapılmıştır. Analog uygulamalar, sayısal uygulamalara göre bir çok noktada farklılıklar göstermektedir. Önerilen model, sıcak taşıyıcı yorulma modelini ve ömür tahmin etme modelini, analog uygulamalarına uygun olarak, tek bir model olarak yeniden geliştirmiştir. Geliştirilen modelin simülasyon sonuçları, ölçüm sonuçları ile doğrulanmaktadır.Anahtar Kelimeler: Güvenilirlik, MOSFET modelleri, sıcak taşıyıcılar, sıcak taşıyıcıların ömür tahmini, SPICE simülasyonu.The focus of this paper is the modeling of parameter degradation reliability of p-MOS transistors due to the hot-carriers under analog operation. Hot-carrier failure cause can initiate the electron trapping/generation and/or interface trap creation mechanism leading to changes of oxide charge and trap densities during device operation. A lot of efforts have been devoted to study the mechanisms due to the hot-carrier and modeling the device degradation due to these effects. However, these modelings are often performed on digital applications. Analog applications differ from digital ones by a number of points. Analog circuit reliability prediction has to take analog circuit design variables such as channel length, biasing conditions, and circuit topography into consideration. In order to achieve highest possible speed, smallest area and smallest power consumption usually L=Lmin are chosen for digital applications. However, for nearly all-analog applications this choice is inadequate because analog circuits usually use long-channel devices, the influence of hot-carrier effects on analog circuit performance has been believed to be minimal and, as a result, has been mostly overlooked. Therefore, the most important device parameters in these two application fields do not coincide. The proposed model includes a hot-carrier degradation model and a lifetime prediction model as a single model suitable for analog applications. The accuracy of the presented models has been verified with experimental data. Keywords: Hot-carrier, hot-carrier life time prediction, MOSFET models, SPICE simulation, reliability

RFID card security for public transportation applications based on a novel neural network analysis of cardholder behavior characteristics

This paper proposes a novel approach that applies neural network forecasting to security for closed-loop prepaid cards based on low-cost technologies such as RFID and 1-Wire. The security vulnerability of low-cost RFID closed-loop prepaid card systems originates mostly from the card itself. Criminal organizations counterfeit or clone card data. Although high-security prepaid cards exist, they are often too expensive for transport ticketing, and even their security is not guaranteed for a well-defined period of time. Therefore, data encryption systems are used widely against counterfeiting with success. However, it has not been possible to develop countermeasures with comparable success against cloning. Our proposed security application uses neural network forecasting to determine the recharge day behavioral characteristics of the cardholder and predict the next time the cardholder will recharge their card. Based on the prediction for the recharge time, the expiration date of the low-cost RFID prepaid card is defined, which is a good countermeasure against cloning. FTDNN, LRNN, and NARX network architectures with one hidden layer are considered in this research. The effects of the network architecture, the number of neurons, the training algorithm, and the prediction performance function on the recharge day forecast are investigated. Experimental results confirm the accuracy of the recharge time forecast and confirm countermeasures against cloning. Our proposed security approach with neural network forecasting is applied with success to the Turkish public transport without an online backend system

A new security approach for public transport application against tag cloning with neural network-based pattern recognition

RFID tags are widely used in situations where their counterfeiting or cloning can bring financial rewards. Cloning is a particular problem because it gets round the sophisticated security measures. This paper describes a neural network-based technique for identifying cloned tickets for a public transport system. It is based on modeling passenger behavior. Cardholders' behavioral characteristics in using public transport are modeled with seven neural network model equations, one for each day of the week, and stored in an RFID card. At the time of use, these model equations or characteristics are employed to predict whether the user is the real owner of the card. Therefore, even if the RFID card is cloned, the cloned card cannot be used because a passenger's behavioral characteristics when using public transport are individual and unique, such as the passenger's signature or style of speech. Therefore, the proposed approach provides high security, especially for low-cost RFID tags

Improving the drain-current expression of BSIM4 for hot-carrier degradation modeling that is suitable for analog applications

The reliability evaluation of MOS transistors is one of the most important subjects in device engineering and VLSI design. The down-scaling of device dimensions adversely affects device reliability and lifetime. Although different factors contribute to device reliability and lifetime, the most influential factor is hot-carrier degradation. Furthermore, hot-carrier degradation affects each application uniquely. In analog applications, hot-carrier degradation is more complex and diverse relative to digital applications. In this study, we improve the BSIM4 drain-current model to develop a hot carrier degradation model that is suitable for both analog and digital applications. Our approach is readily applicable to all process technologies because it depends only on the measured data from fresh and degraded devices. The simulation results of four different process technologies are in excellent agreement with the measured data

On the design of low-frequency filters using CMOS OTAs operating in the subthreshold region

Design considerations on a circuit technique based on subthreshold operation of MOS transistors is described for the realization of low-frequency OTA-C active filters with small capacitance values of the order of 25-400 pF. The circuit technique described is applied to the alpha (8-12 Hz), beta (13-40 Hz), theta (4-8 Hz) and delta (1-4 Hz) band filters for EEG signals. Because of small capacitance values the filter circuit is suitable for realization on a single VLSI chip using the CMOS technology, and enables the user to implement the circuit on implantable biotelemetric applications. (C) 1998 Elsevier Science Ltd. All rights reserved

A NEW COST EFFECTIVE AND RAPID METHOD FOR THE MEASUREMENT OF BLOOD CULTURES

Current automatized blood culture measurement systems are usually based on measurement of carbon dioxide with fluorescence. Long lasting measurement period and high cost are the major disadvantages of such methods. In this study, a new blood culture measurement system that determines growth of blood cultures by monitoring pressure changes in the tube is presented. We could not find any research that investigated equivalent or similar method in English language literature. Our proposed method provides a rapid and inexpensive blood culture measurement. This method uses conventional blood culture tubes and is based on measurement of the slope of the pressure change in the tube. The new method offered here is seven times faster for positive results and 10 times faster for negative results as compared to the current automatized blood culture measurement systems. An economical device, which is able to precisely measure pressure changes of the gasses in the standard measurement tubes, has been designed. By means of this method, much faster and economic pre-assessments can be performed using standard measurement tubes that are more economic

A NEW COST EFFECTIVE AND RAPID METHOD FOR THE MEASUREMENT OF BLOOD CULTURES

Current automatized blood culture measurement systems are usually based on measurement of carbon dioxide with fluorescence. Long lasting measurement period and high cost are the major disadvantages of such methods. In this study, a new blood culture measurement system that determines growth of blood cultures by monitoring pressure changes in the tube is presented. We could not find any research that investigated equivalent or similar method in English language literature. Our proposed method provides a rapid and inexpensive blood culture measurement. This method uses conventional blood culture tubes and is based on measurement of the slope of the pressure change in the tube. The new method offered here is seven times faster for positive results and 10 times faster for negative results as compared to the current automatized blood culture measurement systems. An economical device, which is able to precisely measure pressure changes of the gasses in the standard measurement tubes, has been designed. By means of this method, much faster and economic pre-assessments can be performed using standard measurement tubes that are more economic