PhD Defense: "Efficient Implementation of Neuromorphic Systems with Emerging Device Technologies"

Farnood Merrikh Bayat

April 7th (Tuesday), 4:00pm
Harold Frank Hall (HFH), Rm 4164

Nowadays with unbounded expansion of digital world, powerful information processing systems governed by deep learning algorithms are becoming more and more popular. In this situation, usage of fast, powerful, intelligent and trainable deep learning methods seems critical and unavoidable. However, despite of their inherent structural and conceptual differences, all of these intelligent methods and systems share one common property i.e. having enormous number of trainable parameters. However, from a hardware point of view, the size of a practical computing system is always determined based on available resources. In this dissertation, we study these deep learning methods from a hardware point of view and investigate the possibility of their hardware implementation based on two new emerging technologies i.e. resistive switching and floating gate (flash) devices. For this purpose, memristive devices are fabricated with high density in crossbar structure to create a network which then trained with modified RPROB rule to successfully classify images. In addition, biologically plausible spike-timing dependent plasticity rule and its dependence to initial state is demonstrated experimentally on these nano-scale devices. Similar procedure is followed for the other technology, i.e. flash devices. We modified and fabricated the conventional design of digital flash memories which provide us with the ability of individual programming of floating-gate transistors. Having large-scale neural networks in mind, an efficient and high speed tuning method is developed based on acquired dynamic and static models which are then tested experimentally on commercial devices. We have also experimentally investigated the possibility of implementing vector-to-matrix multiplier using these devices which is the main building block of most deep learning methods. Finally, a multi-layer neural network is designed and fabricated using this technology to classify handwritten digits.

About Farnood Merrikh Bayat:

Farnood Merrikh Bayat received his Bachelor’s degree from K.N. Toosi University (KNTU) of Technology, Tehran, IRAN in 2006 and his Master’s degree from Sharif University of Technology in 2008. Then he joined Prof. Strukov’s group at UCSB in 2012. Currently he is involved in large-scale hardware implementation of neuromorphic systems using memristive devices and floating-gate transistors.

Hosted by: Professor Dmitri Strukov