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
to

218 results found

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, 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

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

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

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

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, ISSN: 0018-9383

In the second part of this series, we propose a physics-based model for describing the temperature dependence of TiOₓ-based memristors, both switching and static. We show that the current-voltage (I-V) characteristics of memristor in the nonswitching regime, indicating a Schottky emission mechanism, can be described by minor modifications to the Schottky current equation. This leads to a physics-based static I-V compact model. Simultaneously, we show that the temperature dependence of the switching dynamics model parameters naturally emerges as a mere scaling factor from the static I-V model. This is a computationally efficient approach, which does not require any additional parameters to extend the switching dynamics model for incorporating thermal dependence.

Journal article

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

Vaidya D, Kothari S, Abbey T, Khiat A, 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, ISSN: 0018-9383

Memristor is a promising device as a fundamental building block for future unconventional system architectures such as neuromorphic computing, reconfigurable logic, and multibit memories. Therefore, to facilitate circuit design using memristors, accurate and efficient models spanning a wide range of programming voltages and temperatures are required. In the first part of this series, we propose a behavioral model for temperature dependence of nonvolatile switching dynamics of TiOₓ memristors. We begin by describing pulsed resistance transients (PRTs) of the memristors and then we use a multistage methodology to establish bias and temperature dependence of the model parameters. The proposed model is then shown to accurately describe the PRT characteristics of Pt/TiOₓ/Au and Pt/TiOₓ/Pt memristors.

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

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 TiO<inf>2−x</inf> memristor devices using high speed pulses, ISSN: 0271-4310

In this demonstration, we present a new electroforming process, along with a new instrument to support this procedure. Memristor arrays will be available for the user to electroform, write, and read the resulting resistive state of the devices.

Conference paper

Szypicyn J, Papavassiliou C, Papandroulidakis G, Merrett G, Serb A, Stathopoulos S, Prodromakis Tet al., 2020, Memristor-enabled reconfigurable integrated circuits

The holy grail of analogue integrated circuit design is adjustable analogue delay element. Of course, all analogue circuits are filters. Internal delays impose overall low-pass character to all circuits so that broadband amplifiers are lowpass filters, while high-pass amplifiers are in fact band-pass filters.

Conference paper

Alexantrou S, Prodromakis T, 2020, Hierarchical AI - From neurons to psychology

The undeniable successes of deep learning (and more generally statistical learning) in bringing pattern matching to the market is still just the tip of the iceberg of AI. In this talk we will look at a very high level overview of AI as a whole and see how it can be interpreted at very different levels of abstraction. Each level of abstraction boasts its own vocabulary and is suited to understanding different aspects of the general problem of artificial intelligence. We will walk through four 'levels of abstraction of AI' ranging from physical implementation all the way to semantic processing, and will investigate how memory technologies can play a vital role in their successful implementation. The aim is to show how innovation in the domain of memory tech can unlock the potential of AI to attack problems much more general than simple pattern matching and thus pave the way to the next wave of AI on the market.

Conference paper

Foster P, Huang J, Serb A, Prodromakis T, Papavassiliou Cet al., 2020, An FPGA based system for interfacing with crossbar arrays, ISSN: 0271-4310

Memristor crossbar arrays offer a novel new approach for designing high density non-volatile memory; however, precise measurement of resistive crossbar elements requires parallel current sensing capability not found in existing instruments. To provide this capability, we have designed and built an FPGA-based crossbar control instrument with independent per-channel biasing and measuring. In this paper, we cover the architecture of this new instrument, its operation and interface, and the results of testing conducted on the instruments pulse driver circuitry.

Conference paper

Stathopoulos S, Michalas L, Khiat A, Serb A, Prodromakis Tet al., 2019, An Electrical Characterisation Methodology for Benchmarking Memristive Device Technologies, SCIENTIFIC REPORTS, Vol: 9, ISSN: 2045-2322

Journal article

Constantoudis V, Papavieros G, Karakolis P, Khiat A, Prodromakis T, Dimitrakis Pet al., 2019, Impact of Line Edge Roughness on ReRAM Uniformity and Scaling, MATERIALS, Vol: 12

Journal article

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