CMOS Transistor-Based Memristor Emulator Circuit Design for High Frequency Applications

In recent time, memristor is gaining widespread attention owing to its potential applications in analog and digital circuits, computer architectures, nano-dimension memories, logic, neuromorphic, and oscillator circuits. However, there is no single component or device available in the market that exhibit memristive behavior. Memristor emulator circuit is introduced to mimic the behavior of a real memristor and emulate its properties. In this work, we propose a transistor-based memristor emulator circuit, which is designed in TSMC 0.18 µm n-well CMOS process technology with a supply voltage of 1.8 V. The results show that the proposed emulator circuit can be switched with a low input voltage of 180 mV and its current-voltage characteristics produces pinched hysteresis loops in the range 15 MHz to 100 MHz, which makes the emulator suitable for high frequency applications. In addition, its layout occupies chip area of 54 µm X 51 µm.

I. Introduction

Memristor is a name that engendered in 1971 from the preliminary work of Leon Chua in nonlinear circuit theory. He represented memristor as a mathematical entity and was regarded as the fourth fundamental element, in addition to resistor, capacitor, and inductor. It is a two terminal passive device that defines the relationship between flux linkage and electric charge [1]. Memristor excites the field of electronics with its ability to retain its last resistance state through modulation of the state variable. This is the most intriguing property because it allows memristor to be used in high density memory devices and systems. Emerging device like memristor often exhibits novel characteristics and tends to manifest advance properties that can be exploited for developing novel designs and applications. Studies have shown that the aggressive scaling of CMOS transistor will bring Moore's law to an end. The most recent nano-CMOS technologies have problems of short channel effects, which results in high leakage current and static power. So, it is highly desirable to explore other scalable and low power devices that would help in continuing the international technology roadmap for semiconductors (ITRS). Following the introduction of memristor into the field of electronics, Chang and Kang [2], in 1976, modelled a memristive system as: \begin{align*} & \mathrm{V}=\mathrm{R}(\mathrm{x}, \ \mathrm{i})\mathrm{i}\tag{1}\\ & \frac{\text{dx}}{\text{dt}}=\mathrm{f}(\mathrm{x}, \ \mathrm{i})\tag{2}\end{align*} where V is the voltage, i is the current, f can be an explicit function of time and is the instantaneous resistance that is dependent on an internal state variable, x, of the device.