Memristor in a Nutshell

Abstract

For almost 150 years, the capacitor (discovered in 1745), the resistor (1827) and the inductor (1831) have been the only fundamental passive devices known and have formed the trinity of fundamental passive circuit elements, which, together with transistors , form the basis of all existing electronic devices and systems. There are only a few fundamental components and each of them performs its own characteristic function that is unique amongst the family of basic components. For example, capacitors store energy in an electric field, inductors store energy in a magnetic field, resistors dissipate electrical energy, and transistors act as switches and amplify electrical energy. It then happened in 1971 when Leon Chua , a professor of electrical engineering at the University of Berkeley , postulated the existence of a fourth fundamental passive circuit element, the memristor (Chua in IEEE Transactions on Circuit Theory 18(5):507–519, 1971). Chua suggested that this fourth device, which was only hypothetical at that point, must exist to complete the conceptual symmetry with the resistor, capacitor and inductor in respect of the four fundamental circuit variables such as voltage, current, charge and flux. He proved theoretically that the behaviour of the memristor could not be substituted by a combination of the other three circuit elements, hence that the memristor a truly fundamental device. This chapter is about the remarkable discovery of the “fourth fundamental passive circuit element”, the memristor. Its name is an amalgamation of the words “memory” and “resistor”, due to the memristor’s properties to act as a resistor with memory. Since the memristor belongs to the family of passive circuit elements, these will be focused here.