Adedotun Adeyemo

  • Adedotun Adeyemo is originally from Nigeria. He joined Oxford Brookes as a research student in January 2014 and his thesis title is ‘Design and Analysis of Reliable Memristor-Based Architectures’.

    How did you hear about Oxford Brookes University?

    I got to know of Oxford Brookes through my MSc dissertation supervisor at the University of Bristol. He was involved in some research with my current supervisor here at Oxford Brookes.

    What attracted you to Oxford Brookes University to conduct your research?

    The nature of the research being carried out by the Advanced Reliable Computer System (ARCoS) group attracted me to Oxford Brookes. ARCoS presented me with the opportunity to work on an emerging technology that involves a mix of electronics and computer science based research.

    What were you doing before?

    After completing a bachelor’s degree in Computer Science (2010) in Nigeria, I worked for two years in an international bank before being awarded a postgraduate (MSc) scholarship by the Nigerian government. I moved to England in 2012 and completed an MSc in Advanced Microelectronic Systems Engineering at the University of Bristol in 2013.

    How easy did you find it to settle into the research environment?

    I had a fairly good research experience during the MSc programme at the University of Bristol. This prior experience made it easy for me to adapt quickly into full research at Oxford Brookes despite the default challenges that comes with research. Adequate support from the faculty, especially my supervisory team went a long way in making my research journey a rewarding one thus far.

    Tell us about your research.

    My research project focuses on design and analysis of architectures made from an emerging technological device called memristor. The memristor, a portmanteau of MEMory and ResISTOR (because it behaves like a linear resistor with memory) is a newly discovered two terminal circuit element (like the existing trio of resistor, capacitor and inductor).

    As transistor draws near to the end of it scaling limit, there is the dire need for the semiconductor industry to explore new technologies to ensure continuous evolution of computing devices according to International Technology Roadmap for Semiconductors (ITRS). Memristor – a novel electronic device is among the emerging technologies tipped to usher in a new generation of computer architectures because of its simple structure, non-volatility and smaller feature size than the transistor. Since HP Lab fabricated the first physical memristor in 2008, there has been an exponential rise in memristor-based research. Since HP Lab’s discovery, several applications of this device have been proposed and demonstrated such as switch to replace Complementary Metal-Oxide Semiconductor (CMOS) transistors in digital logic design, analog circuit design, synapse in neural networks implementation and storage cell in computing memory (primary and secondary). Among these applications, the memristor’s use as a storage cell in memory design is the most widely researched area especially non-volatile memory (Resistive Memory) capable of eliminating the slow boot up process in our PCs.

    Memristor-based memories otherwise known as Resistive Random Access Memory (ReRAM) are fast gaining popularity because of their unprecedented device density that can be achieved via crossbar structures, high retention rate and their simplicity. Resistive RAMs are considered a promising candidate to replace the current Flash memories and Dynamic RAMs (DRAM) in future computers and mobile devices. High density and low power memories can be designed with memristor as the main storage cell, the memristor cell has an estimated area of 4F2 (F is the minimum feature size). Memories are present in all electronic and computing systems; their usage and demand for a more robust type keep increasing. As expected with any technology at its infancy, memristor-based architectures are not foolproof. Memristor-based architectures can successfully replace existing technologies if their reliability problems are effectively resolved. Recent research made it widely evident that reliability aspects of resistive memories radically differ from those of their traditional counterparts. Although resistive memories are more resilient to transient error but their yield and device fault rate will be higher than conventional memories. Memristor-based memories are however susceptible to other problems such as resistance drift, which affects data integrity and current leakages (sneak-path) that leads to excessive power consumption in the system. Sneak-path is a major problem with memristive-based architecture. These leakages are a direct consequence of the bidirectional properties of the memristor (allows current to flow in both direction) and also aided by the crossbar architecture.

    My research project aspires to be a key enabler for the effective deployment of emerging memristor-based resistive memory technologies in all segments of computing systems by innovations towards improving their weakest aspect: reliability. Resistive memories bear the hope of extending the validity of Moore’s law for several decades, in terms of both memory devices density and performance: this is a unique opportunity for the university to stay on the leading edge of computing systems developments for many years. The application of these project results will span most spectrum of the electronics domain. All major industrial players of the semiconductor marketplace have a big interest in next generation memories that are anticipated to resolve the scaling problems of current scaled CMOS technologies. Such emerging memories are planned to be used both as stand-alone products, or integrated in complex chips, in a diverse range of markets from high performance computing (servers and data centres), to mobile devices, to critical electronics for transportation (automotive, railway) as well as avionics (satellites and space-crafts). 

    What do you enjoy about being a research student?

    I love the freedom to work on what I am passionate about. I am excited about the opportunity to be pioneer of novel and game-changing concepts. On the flip side, research can be a daunting task, especially when the project is based on an area that has not been previously explored in depth. Perseverance, diligence and a clear goal keep researchers on course. 

    What are your future plans?

    I find the research and academic experience so far to be an exciting and rewarding experience. I plan to delve into full research after my PhD so as to be consistent contributor to the knowledge domain.