Research

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Our research aims to develop novel ways of computing, circuit design, and reliability for electronic circuits and systems. Our research mainly targets future and emerging technologies.

Contents

Computing with Switching Nano Arrays

As current CMOS-based technology is approaching its anticipated limits, research is shifting to novel forms of nanoscale technologies including molecular-scale self-assembled systems. Unlike conventional CMOS that can be patterned in complex ways with lithography, self-assembled nanoscale systems generally consist of regular structures. Logical functions are achieved with crossbar-type switches. Our model, a network of four- terminal switches, corresponds to this type of switch in a variety of emerging technologies, including nanowire crossbar arrays and magnetic switch-based structures.

Synthesis

In his seminal Master's Thesis, Claude Shannon made the connection between Boolean algebra and switching circuits. He considered two-terminal switching networks to implement any Boolean function that is the foundation of CMOS circuit design techniques. In this work, we have considered four-terminal switching networks to implement any Boolean function that aims to be a foundation of nano array based circuit design techniques.

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Reliability

We have devised a novel framework for digital computation with networks of nanoscale switches with high defect rates, based on the mathematical phenomenon of percolation. With random connectivity, percolation gives rise to a sharp non-linearity in the probability of global connectivity as a function of the probability of local connectivity. This phenomenon is exploited to compute Boolean functions robustly, in the presence of random defects.

Selected Publications
title: Logic Synthesis for Switching Lattices
authors: Mustafa Altun and Marc Riedel
appeared in: IEEE Transactions on Computers,
Vol. 61, Issue 11, pp. 1588–1600, 2012.
presented at: Design Automation Conference, Anaheim, CA, 2010.
presented at: International Conference on Computational Modelling of
Nanostructured Materials (ICCMNM)-FIAS
, Frankfurt, Germany, 2013.

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title: Synthesizing Logic with Percolation in Nanoscale Lattices
authors: Mustafa Altun and Marc Riedel
appeared in: International Journal of Nanotechnology and Molecular Computation,
Vol. 3, Issue 2, pp. 12–30, 2011.
presented at: Design Automation Conference, San Francisco, CA, 2009.

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Funding Projects
title: Synthesis and Reliability Analysis of Nano Switching Arrays
agency & program: TUBITAK Career Program (3501)
duration: 2014-2017
title: Logic Circuit Design for Nano Arrays
agency & program: TUBITAK Undergraduate Students Research Projects Support Program (2209/A)
duration: 01/2014-07/2014


Reliability of Electronic Boards

The rapid developments in electronics, especially in the last decade, have initiated the inception of electronics reliability . Conventionally used accelerated reliability tests have lost their significance; time consuming and expensive feature of these tests is against the demands of today's very rapid electronic product cycles. In this study, we propose less costly, yet accurate, reliability prediction techniques using field return data, new accelerated test methodologies, and physics of failure based simulations. We cooperate with one of the Europe’s largest household appliances companies Arçelik A.Ş..

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Field Data Analysis and Prediction

We perform field return data analysis of electronic boards having two steps filtering and modeling. In the first step of filtering we eliminate improper data, consisting of obvious and hidden errors, from the whole field return data. In the second step of modeling, we use the filtered data to develop our piecewise reliability model. Our reliability analysis is based on a new technique that deals with forward and backward time analysis of the data.

We precisely predict the reliability performance of electronic boards throughout the warranty period by using very short-term field return data. For electronic boards targeted in this study, warranty period is 3 years, and we use field data of 3 months.

Selected Publications
title: Warranty Forecasting of Electronic Boards using Short-term Field Data
authors: Vehbi Comert, Mustafa Altun, Mustafa Nadar, and Ertunc Erturk
accepted at: Reliability and Maintainability Symposium, Palm Harbor, FL, 2015.

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title: Reliability Prediction of Electronic Boards by Analyzing Field Return Data
authors: Vehbi Comert, Hadi Yadavari, Mustafa Altun, and Ertunc Erturk
presented at: European Safety and Reliability Conference, Wroclaw ,Poland, 2014.

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Funding Projects
title: A reliability Methodology for Appliance Electronic Cards
agency & program: TUBITAK University-Industry Collaboration Grant Program (1505)
duration: 2013-2015
title: Gate Oxide Breakdown Failure Mechanism of CMOS Transistors
agency & program: TUBITAK Industry Oriented Senior Project Support Program (2241/A)
duration: 2013-2014


Quantum Circuit Design

Synthesis and Optimization

We propose a fast synthesis algorithm that implements any given reversible Boolean function with quantum gates. Instead of an exhaustive search on every given function, our algorithm creates a library of essential functions and performs sorting. As an example, to implement 4 bit circuits we only use 120 essential functions out of all 20922789888000 functions.

By considering the physical structure of quantum gates, we show that optimum area solutions proposed in the literature are not actually optimum; they can be improved.

Selected Publications
title: An Efficient Algorithm to Synthesize Quantum Circuits and Optimization
authors: Ömercan Susam and Mustafa Altun
submitted to: IEEE International Conference on Electronics Circuits and Systems,
Marseille, France, 2014.

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Funding Projects
title: Quantum Circuit Design and Computation
agency & program: Istanbul Technical University Research Support Program (ITU-BAP)
duration: 2014-2015
title: Synthesizing Quantum Circuits
agency & program: TUBITAK MSc Scholarship Program in Priority Areas (2210/C)
duration: 2014-2015


Analog Circuit Design

Positive Feedback

The conventional wisdom is that analog circuits should not include positive feedback loops. As controversial as it seems, we have successfully used positive feedback for impedance improvement in a current amplifier. With adding few transistors we have achieved very low input resistance values. Additionally, we have proposed a new fully-differential current amplifier and tested it in a filter application.

Selected Publications
title: Design of a Fully Differential Current Mode Operational Amplifier with its Filter Applications
authors: Mustafa Altun and Hakan Kuntman
appeared in: AEU International Journal of Electronics and Communications,
Vol. 62, Issue 3, pp. 39–44, 2008.
presented at: ACM Great Lakes Symposium on VLSI (GLSVLSI), Stresa, Italy, 2007.

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Discrete Mathematics

Self Duality Problem

The problem of testing whether a monotone Boolean function in irredundant disjuntive normal form (IDNF) is self-dual is one of few problems in circuit/time complexity whose precise tractability status is unknown. We have focused on this famous problem. We have shown that monotone self-dual Boolean functions in IDNF do not have more variables than disjuncts. We have proposed an algorithm to test whether a monotone Boolean function in IDNF with n variables and n disjuncts is self-dual. The algorithm runs in O(n^3) time.

Selected Publications
title: A Study on Monotone Self-dual Boolean Functions
authors: Mustafa Altun and Marc Riedel
submitted  to: ..., 2014.

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