Imperial College London

Professor Themis Prodromakis

Faculty of EngineeringDepartment of Electrical and Electronic Engineering

Honorary Research Fellow
 
 
 
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Contact

 

+44 (0)20 7594 0840t.prodromakis Website

 
 
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Location

 

B422Bessemer BuildingSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
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223 results found

Simanjuntak FM, Hsu C-L, Abbey T, Chang L-Y, Rajasekaran S, Prodromakis T, Tseng T-Yet al., 2021, Conduction channel configuration controlled digital and analog response in TiO2-based inorganic memristive artificial synapses, APL MATERIALS, Vol: 9, ISSN: 2166-532X

Journal article

Lanza M, Waser R, Ielmini D, Yang JJ, Goux L, Suñe J, Kenyon AJ, Mehonic A, Spiga S, Rana V, Wiefels S, Menzel S, Valov I, Villena MA, Miranda E, Jing X, Campabadal F, Gonzalez MB, Aguirre F, Palumbo F, Zhu K, Roldan JB, Puglisi FM, Larcher L, Hou TH, Prodromakis T, Yang Y, Huang P, Wan T, Chai Y, Pey KL, Raghavan N, Dueñas S, Wang T, Xia Q, Pazos Set al., 2021, Standards for the Characterization of Endurance in Resistive Switching Devices, ACS Nano, Vol: 15, Pages: 17214-17231, ISSN: 1936-0851

Resistive switching (RS) devices are emerging electronic components that could have applications in multiple types of integrated circuits, including electronic memories, true random number generators, radiofrequency switches, neuromorphic vision sensors, and artificial neural networks. The main factor hindering the massive employment of RS devices in commercial circuits is related to variability and reliability issues, which are usually evaluated through switching endurance tests. However, we note that most studies that claimed high endurances >106 cycles were based on resistance versus cycle plots that contain very few data points (in many cases even <20), and which are collected in only one device. We recommend not to use such a characterization method because it is highly inaccurate and unreliable (i.e., it cannot reliably demonstrate that the device effectively switches in every cycle and it ignores cycle-to-cycle and device-to-device variability). This has created a blurry vision of the real performance of RS devices and in many cases has exaggerated their potential. This article proposes and describes a method for the correct characterization of switching endurance in RS devices; this method aims to construct endurance plots showing one data point per cycle and resistive state and combine data from multiple devices. Adopting this recommended method should result in more reliable literature in the field of RS technologies, which should accelerate their integration in commercial products.

Journal article

Maheshwari S, Stathopoulos S, Wang J, Serb A, Pan Y, Mifsud A, Leene LB, Shen J, Papavassiliou C, Constandinou TG, Prodromakis Tet al., 2021, Design flow for hybrid CMOS/memristor systems--Part I: modeling and verification steps, IEEE Transactions on Circuits and Systems I: Regular Papers, Vol: 68, Pages: 4862-4875, ISSN: 1549-8328

Memristive technology has experienced explosive growth in the last decade, with multiple device structures being developed for a wide range of applications. However, transitioning the technology from the lab into the marketplace requires the development of an accessible and user-friendly design flow, supported by an industry-grade toolchain. In this work, we demonstrate the behaviour of our in-house fabricated custom memristor model and its integration into the Cadence Electronic Design Automation (EDA) tools for verification. Various input stimuli were given to record the memristive device characteristics both at the device level as well as the schematic level for verification of the memristor model. This design flow from device to industrial level EDA tools is the first step before the model can be used and integrated with Complementary Metal-Oxide Semiconductor (CMOS) in applications for hybrid memristor/CMOS system design.

Journal article

Maheshwari S, Stathopoulos S, Wang J, Serb A, Pan Y, Mifsud A, Leene LB, Shen J, Papavassiliou C, Constandinou TG, Prodromakis Tet al., 2021, Design flow for hybrid CMOS/memristor systems--Part II: circuit schematics and layout, IEEE Transactions on Circuits and Systems I: Regular Papers, Vol: 68, Pages: 4876-4888, ISSN: 1549-8328

\normalsize The capability of in-memory computation, reconfigurability, low power operation as well as multistate operation of the memristive device deems them a suitable candidate for designing electronic circuits with a broad range of applications. Besides, the integrability of memristor with CMOS enables it to use in logic circuits too. In this work, we demonstrate with examples the design flow for memristor-based electronics, after the custom memristor model already being integrated and validated into our chosen Computer-Aided Design (CAD) tool to performing layout-versus-schematic and post-layout checks including the memristive device. We envisage that this step-by-step guide to introducing memristor into the standard integrated circuit design flow will be a useful reference document for both device developers who wish to benchmark their technologies and circuit designers who wish to experiment with memristive-enhanced systems.

Journal article

Manouras V, Stathopoulos S, Serb A, Prodromakis Tet al., 2021, Technology agnostic frequency characterization methodology for memristors., Sci Rep, Vol: 11

Over the past decade, memristors have been extensively studied for a number of applications, almost exclusively with DC characterization techniques. Studies of memristors in AC circuits are sparse, with only a few examples found in the literature, and characterization methods with an AC input are also sparingly used. However, publications concerning the usage of memristors in this working regime are currently on the rise. Here we propose a "technology agnostic" methodology for memristor testing in certain frequency bands. A measurement process is initially proposed, with specific instructions on sample preparation, followed by an equipment calibration and measurement protocol. This article is structured in a way which aims to facilitate the usage of any available measurement equipment and it can be applied on any type of memristive technology. The second half of this work is centered around the representation of data received from following this process. Bode plot and Nyquist plot representations are considered and the information received from them is evaluated. Finally, examples of expected behaviors are given, characterizing simulated scenarios which represent different internal device models and different switching behaviors, such as capacitive or inductive switching. This study aims at providing a cohesive way for memristor characterization, to be used as a good starting point for frequency applications, and for understanding physical processes inside the devices, by streamlining the measuring process and providing a frame in which data representation and comparison will be facilitated.

Journal article

Vaidya D, Kothari S, Abbey T, Stathopoulos S, Michalas L, Serb A, Prodromakis Tet al., 2021, Compact Modeling of the Switching Dynamics and Temperature Dependencies in TiOx Memristors-Part II: Physics-Based Model, IEEE TRANSACTIONS ON ELECTRON DEVICES, Vol: 68, Pages: 4885-4890, ISSN: 0018-9383

Journal article

Vaidya D, Kothari S, Abbey T, Stathopoulos S, Michalas L, Serb A, Prodromakis Tet al., 2021, Compact Modeling of the Switching Dynamics and Temperature Dependencies in TiOx-Based Memristors - Part I: Behavioral Model, IEEE TRANSACTIONS ON ELECTRON DEVICES, Vol: 68, Pages: 4877-4884, ISSN: 0018-9383

Journal article

Serb A, Khiat A, Prodromakis T, 2021, Practical demonstration of a RRAM memory fuse, International Journal of Circuit Theory and Applications, Vol: 49, Pages: 2363-2372, ISSN: 0098-9886

Since its inception, the resistive random access memory (RRAM) fuse has been a good example of how small numbers of RRAM devices can be combined to obtain useful behaviors unachievable by individual devices. In this work, we link the RRAM fuse concept with that of the complementary resistive switch (CRS), exploit that link to experimentally demonstrate a practical RRAM fuse using TiOx-based RRAM cells, and explain its basic operational principles. The fuse is stimulated by trains of identical pulses where successive pulse trains feature opposite polarities. In response, we observe a gradual (analogue) drop in resistive state followed by a gradual recovery phase regardless of input stimulus polarity, echoing traditional, binary CRS behavior. This analogue switching property opens the possibility of operating the RRAM fuse as a single-component step change detector. Moreover, we discover that the characteristics of the individual RRAM devices used to demonstrate the RRAM fuse concept in this work allow our fuse to be operated in a regime where one of the two constituent devices can be switched largely independently from the other. This property, not present in the traditional CRS, indicates that the inherently analogue RRAM fuse architecture may support additional operational flexibility through, for example, allowing finer control over its resistive state.

Journal article

Wang J, Serb A, Papavassiliou C, Maheshwari S, Prodromakis Tet al., 2021, Analysing and measuring the performance of memristive integrating amplifiers, INTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS, Vol: 49, Pages: 3507-3525, ISSN: 0098-9886

Journal article

Manouras V, Stathopoulos S, Garlapati SK, Serb A, Prodromakis Tet al., 2021, Frequency Response of Metal-Oxide Memristors, IEEE TRANSACTIONS ON ELECTRON DEVICES, Vol: 68, Pages: 3636-3642, ISSN: 0018-9383

Journal article

Leung OM, Schoetz T, Prodromakis T, Ponce de Leon Cet al., 2021, Review-Progress in Electrolytes for Rechargeable Aluminium Batteries, JOURNAL OF THE ELECTROCHEMICAL SOCIETY, Vol: 168, ISSN: 0013-4651

Journal article

Maheshwari S, Serb A, Papavassiliou C, Prodromakis Tet al., 2021, An Adiabatic Regenerative Capacitive Artificial Neuron, 2021 IEEE International Symposium on Circuits and Systems (ISCAS), Publisher: IEEE

Conference paper

Wang J, Serb A, Papavassiliou C, Prodromakis Tet al., 2021, Accounting for Memristor I-V Non-Linearity in Low Power Memristive Amplifiers, 2021 IEEE International Symposium on Circuits and Systems (ISCAS), Publisher: IEEE

Conference paper

Prinzie J, Simanjuntak FM, Leroux P, Prodromakis Tet al., 2021, Low-power electronic technologies for harsh radiation environments, NATURE ELECTRONICS, Vol: 4, Pages: 243-253, ISSN: 2520-1131

Journal article

Simanjuntak FM, Chandrasekaran S, Panda D, Rajasekaran S, Rullyani C, Madhaiyan G, Prodromakis T, Tseng T-Yet al., 2021, Negative effect of cations out-diffusion and auto-doping on switching mechanisms of transparent memristor devices employing ZnO/ITO heterostructure, APPLIED PHYSICS LETTERS, Vol: 118, ISSN: 0003-6951

Journal article

Stathopoulos S, Tzouvadaki I, Prodromakis T, 2021, Author Correction: UV induced resistive switching in hybrid polymer metal oxide memristors., Sci Rep, Vol: 11

Journal article

Saleem A, Simanjuntak FM, Chandrasekaran S, Rajasekaran S, Tseng T-Y, Prodromakis Tet al., 2021, Transformation of digital to analog switching in TaOx-based memristor device for neuromorphic applications, APPLIED PHYSICS LETTERS, Vol: 118, ISSN: 0003-6951

Journal article

Shen J, Stathopoulos S, Prodromakis T, Papavassiliou Cet al., 2021, A reconfigurable CMOS-memristor active inductor, ISCAS 2020, ISSN: 0271-4310

A methodology is introduced here to exploit the programmability of the memristors in order to realize reconfigurable monolithic analogue circuit elements. Classical network synthesis methods are used to synthesize adjustable active inductors with inductance values exceeding those of on-chip passives by several orders of magnitude. In this paper, a wide range of active inductance values are obtained by employing memristor to control the biasing current of operational transconductance amplifiers used to implement gyrators. The gyration constant of the proposed gyrator will be linearly controlled by memristance state. The implementation of the designed circuit is realized in 0.18µm commercially available complementary metal-oxide-semiconductor (CMOS) technology from TSMC. Circuit performance is simulated using Cadence Virtuoso. The utilized off-chip memristor is a metal-oxide bi-layer memristor which exhibits a non-volatile memristance range of 4.7kΩ to 170kΩ. The active inductance range achieved is from approximately 95µH to 1.55mH with an inductive bandwidth of 69MHz and 18MHz respectively. The total power consumption is between 0.21mW to 1.95mW depending on the memristance and equivalent inductance.

Conference paper

Pan Y, Foster P, Serb A, Prodromakis Tet al., 2021, A RRAM-based associative memory cell, ISSN: 0271-4310

In general, intelligent systems require knowledge databases storing memory associations for mimicking the capabilities of the human brain. Conventional associative memory cells are constructed based on SRAM, a type of volatile memory consisting of large numbers of transistors per stored bit. Here, we present an energy efficient, robust and hardware friendly-associative memory cell design that we designate RC-XNOR-Z. It is based on creating a tuneable RC constant with the help of a modifiable resistance element (RRAM), plus a simplified XNOR gate for generating the output. The overall design has a total component count of 6T1C1R (6 transistors, 1 capacitor, 1 RRAM device), is non-volatile, is designed to work with RRAM devices with very low ON/OFF ratio (≈4), avoids high current DC paths during misses and operates under power supply of 0.95V. Furthermore, we show expected simulated power dissipation per miss including refresh in the order of single-digit nW/bit and power dissipation/hit in the order of 10 µW, which for a clock rate of 1GHz translates into aJ and 100s of pJ dissipation accordingly. This is competitive with state of art DRAM and SRAM.

Conference paper

Stathopoulos S, Tzouvadaki I, Prodromakis T, 2020, UV induced resistive switching in hybrid polymer metal oxide memristors, SCIENTIFIC REPORTS, Vol: 10, ISSN: 2045-2322

Journal article

Giotis C, Serb A, Stathopoulos S, Michalas L, Khiat A, Prodromakis Tet al., 2020, Bidirectional Volatile Signatures of Metal-Oxide Memristors-Part I: Characterization, IEEE TRANSACTIONS ON ELECTRON DEVICES, Vol: 67, Pages: 5158-5165, ISSN: 0018-9383

Journal article

Giotis C, Serb A, Stathopoulos S, Prodromakis Tet al., 2020, Bidirectional Volatile Signatures of Metal-Oxide Memristors-Part II: Modeling, IEEE TRANSACTIONS ON ELECTRON DEVICES, Vol: 67, Pages: 5166-5173, ISSN: 0018-9383

Journal article

Buratti E, Sanzari I, Dinelli F, Prodromakis T, Bertoldo Met al., 2020, Formation and Stability of Smooth Thin Films with Soft Microgels Made of Poly(N-Isopropylacrylamide) and Poly(Acrylic Acid), POLYMERS, Vol: 12

Journal article

Tzouvadaki I, Stathopoulos S, Abbey T, Michalas L, Prodromakis Tet al., 2020, Monitoring PSA levels as chemical state-variables in metal-oxide memristors, SCIENTIFIC REPORTS, Vol: 10, ISSN: 2045-2322

Journal article

Moutoulas E, Hamidullah M, Prodromakis T, 2020, Surface Acoustic Wave Resonators for Wireless Sensor Network Applications in the 433.92 MHz ISM Band, SENSORS, Vol: 20

Journal article

Serb A, Corna A, George R, Khiat A, Rocchi F, Reato M, Maschietto M, Mayr C, Indiveri G, Vassanelli S, Prodromakis Tet al., 2020, Author Correction: Memristive synapses connect brain and silicon spiking neurons., Sci Rep, Vol: 10

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Journal article

Sanzari I, Buratti E, Huang R, Tusan CG, Dinelli F, Evans ND, Prodromakis T, Bertoldo Met al., 2020, Poly(N-isopropylacrylamide) based thin microgel films for use in cell culture applications, SCIENTIFIC REPORTS, Vol: 10, ISSN: 2045-2322

Journal article

Serb A, Corna A, George R, Khiat A, Rocchi F, Reato M, Maschietto M, Mayr C, Indiveri G, Vassanelli S, Prodromakis Tet al., 2020, Memristive synapses connect brain and silicon spiking neurons, SCIENTIFIC REPORTS, Vol: 10, ISSN: 2045-2322

Journal article

Serb A, Kobyzev I, Wang J, Prodromakis Tet al., 2020, A semi-holographic hyperdimensional representation system for hardware-friendly cognitive computing, PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES, Vol: 378, ISSN: 1364-503X

Journal article

Foster P, Huang J, Serb A, Prodromakis T, Papavassiliou Cet al., 2020, Live Demonstration: Electroforming of TiO2-x memristor devices using high speed pulses, IEEE International Symposium on Circuits and Systems (ISCAS), Publisher: IEEE, ISSN: 0271-4302

Conference paper

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