Publications
180 results found
Houssein A, Drakakis E, 2016, MOS-only reduced-order ELIN cochlear channels: comparative performance evaluation, International Journal of Circuit Theory and Applications, Vol: 45, Pages: 731-743, ISSN: 0098-9886
his paper introduces and applies practical area-reduction techniques on the analogue, externally linear-internally nonlinear, complementary metal-oxide semiconductor (CMOS) implementation of a cochlear channel. This channel is constructed on the basis of the biomimetic auditory filter called One-Zero Gammatone Filter, and it has been synthesised using ultra-low power Class-AB biquadratic filters, which employ MOS transistors that operate in their weak inversion regime. The realisation of linear capacitors with appropriately configured MOS transistors, the order reduction of the One-Zero Gammatone Filter transfer function and the employment of hyperbolic sine companding filters can lead to area reductions that range from 61.8% up to 91.9% of the original size. Comparative simulation results highlight the trade-offs between performance, linearity, noise and power consumption of the designs.
Koymen I, Glaros KN, Drakakis EM, 2016, Class A and Class AB CMOS-Only Nanopower Memristive Dynamics Emulators, INTERNATIONAL JOURNAL OF BIFURCATION AND CHAOS, Vol: 26, ISSN: 0218-1274
Papadimitriou KI, Houssein A, Drakakis EM, 2016, Analytical study, performance optimisation and design rules for customary static and dynamic subthreshold MOS translinear topologies, Microelectronics Journal, Vol: 53, Pages: 177-193, ISSN: 0026-2692
This paper aims to provide qualitative and quantitative answers to questions related to the impact of transistor-level design parameters upon the performance and accuracy of static and dynamic translinear (TL) circuits in subthreshold CMOS. A methodical, step-by-step, symbolic analysis, exploiting a simplified EKV-based approximation is performed upon customary static TL topologies, including the four MOS transistor (MOST) multiplier/divider, the squarer circuit and the alternating formation of a six MOST multiplier/divider. The logarithmic integrator is treated as a typical dynamic TL analysis example. The produced EKV-based symbolic analysis results are compared against the ideally expected behaviours and Spectre®-BSIM3V3model-simulations. The satisfying agreement between the proposed EKV-based model and Spectre simulator allowed us to proceed further and investigate the conditions under which optimal behaviour is achieved. Optimisation techniques, based on MOSTs' geometrical parameters combinations, resulted in the articulation of practical design rules.
Papadimitriou K, Wang C, Rogers M, et al., 2016, High-Performance Bioinstrumentation for Real-Time Neuroelectrochemical Traumatic Brain Injury Monitoring, Frontiers in Human Neuroscience, Vol: 10, ISSN: 1662-5161
Traumatic brain injury (TBI) has been identified as an important cause of death and severe disability in all age groups and particularly in children and young adults. Central to TBI’s devastation is a delayed secondary injury that occurs in 30-40% of TBI patients each year, while they are in the hospital Intensive Care Unit (ICU). Secondary injuries reduce survival rate after TBI and usually occur within 7 days post-injury. State-of-art monitoring of secondary brain injuries benefits from the acquisition of high-quality and time-aligned electrical data i.e. ElectroCorticoGraphy (ECoG) recorded by means of strip electrodes placed on the brain’s surface, and neurochemical data obtained via rapid sampling microdialysis and microfluidics-based biosensors measuring brain tissue levels of glucose, lactate and potassium. This article progresses the field of multi-modal monitoring of the injured human brain by presenting the design and realisation of a new, compact, medical-grade amperometry, potentiometry and ECoG recording bioinstrumentation. Our combined TBI instrument enables the high-precision, real-time neuroelectrochemical monitoring of TBI patients, who have undergone craniotomy neurosurgery and are treated sedated in the ICU. Electrical and neurochemical test measurements are presented, confirming the high-performance of the reported TBI bioinstrumentation.
Georgiou PS, Yaliraki SN, Drakakis EM, et al., 2016, Window functions and sigmoidal behaviour of memristive systems, International Journal of Circuit Theory and Applications, Vol: 44, Pages: 1685-1696, ISSN: 0098-9886
Summary: A common approach to model memristive systems is to include empirical window functions to describe edge effects and nonlinearities in the change of the memristance. We demonstrate that under quite general conditions, each window function can be associated with a sigmoidal curve relating the normalised time-dependent memristance to the time integral of the input. Conversely, this explicit relation allows us to derive window functions suitable for the mesoscopic modelling of memristive systems from a variety of well-known sigmoidals. Such sigmoidal curves are defined in terms of measured variables and can thus be extracted from input and output signals of a device and then transformed to its corresponding window. We also introduce a new generalised window function that allows the flexible modelling of asymmetric edge effects in a simple manner.
Yang G, Lyon RF, Drakakis EM, 2015, Psychophysical Evaluation of An Ultra-Low Power, Analog Biomimetic Cochlear Implant Processor Filterbank Architecture With Across Channels AGC, IEEE-ACM TRANSACTIONS ON AUDIO SPEECH AND LANGUAGE PROCESSING, Vol: 23, Pages: 2465-2473, ISSN: 2329-9290
Houssein A, Papadimitriou KI, Drakakis EM, 2015, A 1.26 mu W Cytomimetic IC Emulating Complex Nonlinear Mammalian Cell Cycle Dynamics: Synthesis, Simulation and Proof-of-Concept Measured Results, IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS, Vol: 9, Pages: 543-554, ISSN: 1932-4545
Wu W, Vitharana K, Gorgy T, et al., 2015, A Method for Voltage Measurements of Cancerous vs Non-cancerous Omentum, 37th Annual International Conference of the IEEE-Engineering-in-Medicine-and-Biology-Society (EMBC), Publisher: IEEE, Pages: 7514-7517, ISSN: 1557-170X
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- Citations: 2
Prokopiou AN, Drakakis EM, 2015, Quantitative Analysis Linking Inner Hair Cell Voltage Changes and Postsynaptic Conductance Change: A Modelling Study, BioMed Research International, Vol: 2015, Pages: 1-21, ISSN: 2314-6133
Georgiou PS, Koeymen I, Drakakis EM, 2015, Noise Properties of Ideal Memristors, IEEE International Symposium on Circuits and Systems (ISCAS), Publisher: IEEE, Pages: 1146-1149, ISSN: 0271-4302
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- Citations: 5
Georgiou PS, Barahona M, Yaliraki SN, et al., 2014, On memristor ideality and reciprocity, Microelectronics Journal, Vol: 45, Pages: 1363-1371, ISSN: 0026-2692
Yang G, Lyon RF, Drakakis EM, 2014, A 6uW per Channel Analog Biomimetic Cochlear Implant Processor Filterbank Architecture With Across Channels AGC, IEEE Transactions on Biomedical Circuits and Systems, Vol: 9, Pages: 72-86, ISSN: 1932-4545
Fotopoulou C, Gorgy T, Paterson A, et al., 2014, Molecular physiology monitoring of ovarian cancer ex vivo., Annual Meeting of the American-Society-of-Clinical-Oncology (ASCO) / Clinical Science Symposium on Predicting and Improving Adverse Outcomes in Older Adults with Cancer, Publisher: LIPPINCOTT WILLIAMS & WILKINS, 530 WALNUT ST, PHILADELPHIA, PA 19106-3621 USA, ISSN: 1048-891X
Kis Z, Towhidi L, Ip H, et al., 2014, An in-situ electroporation and flow device for mechanotransduction studies, Microarrays: Principles, Applications and Technologies, Editors: James V Rogers, Pages: 49-68, ISBN: 978-1-62948-669-7
Koymen I, Drakakis EM, 2014, CMOS-Based Nanopower Memristor Dynamics Emulator, 14th International Workshop on Cellular Nanoscale Networks and their Applications (CNNA), Publisher: IEEE, ISSN: 2165-0179
Kardoulaki EM, Glaros KN, Katsiamis AG, et al., 2014, A Simulation Study of High-Order CMOS Hyperbolic Sine Filters, International Journal of Circuit Theory and Applications, Vol: 42, Pages: 1033-1050, ISSN: 1097-007X
Papadimitriou KI, Liu SC, Indiveri G, et al., 2014, Neuromorphic log-domain silicon synapse circuits obey bernoulli dynamics: a unifying tutorial analysis., Frontiers in Neuroscience, Vol: 8, ISSN: 1662-453X
The field of neuromorphic silicon synapse circuits is revisited and a parsimonious mathematical framework able to describe the dynamics of this class of log-domain circuits in the aggregate and in a systematic manner is proposed. Starting from the Bernoulli Cell Formalism (BCF), originally formulated for the modular synthesis and analysis of externally linear, time-invariant logarithmic filters, and by means of the identification of new types of Bernoulli Cell (BC) operators presented here, a generalized formalism (GBCF) is established. The expanded formalism covers two new possible and practical combinations of a MOS transistor (MOST) and a linear capacitor. The corresponding mathematical relations codifying each case are presented and discussed through the tutorial treatment of three well-known transistor-level examples of log-domain neuromorphic silicon synapses. The proposed mathematical tool unifies past analysis approaches of the same circuits under a common theoretical framework. The speed advantage of the proposed mathematical framework as an analysis tool is also demonstrated by a compelling comparative circuit analysis example of high order, where the GBCF and another well-known log-domain circuit analysis method are used for the determination of the input-output transfer function of the high (4(th)) order topology.
Kardoulaki EM, Glaros KN, Degenaar P, et al., 2013, Measured hyperbolic-sine (sinh) CMOS results: A high-order 10 Hz-1 kHz notch filter for 50/60 Hz noise, Microelectronics Journal, Vol: 44, Pages: 1268-1277, ISSN: 0026-2692
Papadimitriou KI, Stan G-B, Drakakis EM, 2013, Systematic computation of non-linear cellular and molecular dynamics with low-power cytomimetic circuits: A simulation study, PLoS ONE, Vol: 8, ISSN: 1932-6203
This paper presents a novel method for the systematic implementation of low-power microelectronic circuits aimed at computing nonlinear cellular and molecular dynamics. The method proposed is based on the Nonlinear Bernoulli Cell Formalism (NBCF), an advanced mathematical framework stemming from the Bernoulli Cell Formalism (BCF) originally exploited for the modular synthesis and analysis of linear, time-invariant, high dynamic range, logarithmic filters. Our approach identifies and exploits the striking similarities existing between the NBCF and coupled nonlinear ordinary differential equations (ODEs) typically appearing in models of naturally encountered biochemical systems. The resulting continuous-time, continuous-value, low-power CytoMimetic electronic circuits succeed in simulating fast and with good accuracy cellular and molecular dynamics. The application of the method is illustrated by synthesising for the first time microelectronic CytoMimetic topologies which simulate successfully: 1) a nonlinear intracellular calcium oscillations model for several Hill coefficient values and 2) a gene-protein regulatory system model. The dynamic behaviours generated by the proposed CytoMimetic circuits are compared and found to be in very good agreement with their biological counterparts. The circuits exploit the exponential law codifying the low-power subthreshold operation regime and have been simulated with realistic parameters from a commercially available CMOS process. They occupy an area of a fraction of a square-millimetre, while consuming between 1 and 12 microwatts of power. Simulations of fabrication-related variability results are also presented.
Georgiou PS, Barahona M, Yaliraki SN, et al., 2013, Ideal Memristors as Reciprocal Elements, Proceedings of the 20th IEEE International Conference on Electronics, Circuits, and Systems (ICECS), Pages: 301-304
Yue X, Krapp HG, Drakakis EM, 2013, An output code offset-free comparator for SAR ADCs based on non-linear preamplifier and CMOS inverters, Microelectronics Journal, Vol: 44, Pages: 414-420, ISSN: 0026-2692
Eftekhar A, Toumazou C, Drakakis EM, 2013, Empirical Mode Decomposition: Real-Time Implementation and Applicationss, Journal of Signal Processing Systems, Vol: 73, Pages: 43-58, ISSN: 1939-8018
Georgiou PS, Barahona M, Yaliraki SN, et al., 2012, Device Properties of Bernoulli Memristors, Proceedings of the IEEE, Vol: 100, Pages: 1938-1950, ISSN: 0018-9219
Katsiamis AG, Drakakis EM, Lyon RF, 2012, Bio-inspired CMOS Cochlea, Encyclopaedia of Nanotechnology, Publisher: Springer Netherlands, Pages: 219-243, ISBN: 9789048197514
Georgiou PS, Yaliraki SN, Drakakis EM, et al., 2012, Quantitative Measure of Hysteresis for Memristors through Explicit Dynamics, Proceedings of the Royal Society of London A: Mathematical, Physical and Engineering Sciences, Vol: 468, Pages: 2210-2229, ISSN: 1471-2946
Wang L, Drakakis EM, Duan S, et al., 2012, Memristor Model and its Application for Chaos Generation, International Journal of Bifurcation and Chaos, Vol: 22, Pages: 1250205-1-1250205-14, ISSN: 0218-1274
Glaros KN, Drakakis EM, 2012, Self-Biased Logarithmic Photoreceptor With Low Settling Time, IEEE Transactions on Circuits and Systems Part I: Regular Papers, Vol: 59, Pages: 2244-2251, ISSN: 1549-8328
Papadimitriou KI, Drakakis EM, 2012, CMOS Weak-inversion Log-domain Glycolytic Oscilllator: A Cytomimetic Circuit Example, International Journal of Circuit Theory and Applications, Vol: 42, Pages: 173-194, ISSN: 1097-007X
Glaros KN, Drakakis EM, 2012, A Sub-mW Fully-Integrated Pulse Oximeter Front-End, IEEE Transactions on Biomedical Circuits and Systems, Vol: 7, Pages: 363-375, ISSN: 1932-4545
Ip HMD, Drakakis EM, Bharath AA, 2011, Preliminary results from an analog implementation of first-order TDCNN dynamics, International Journal of Circuit Theory and Applications, Vol: 39, Pages: 665-678, ISSN: 0098-9886
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