A Novel Hybrid CMOS-Memristor Based 2-Bit Magnitude Comparator using Memristor Ratioed Logic Universal Gate for Low Power Applications

In recent years, memristor-based digital circuit design has become one of the prime focuses for low power, area-efficient VLSI design. A comparator is a combinational circuit used in complex ALU for the comparison of n-bit numbers. The unique hybrid 2bit CMOS-based comparator with Memristor Ratioed Logic Universal Gates has been implemented in this study (MRLUG). The proposed 2-bit magnitude comparator is verified by theoretical analysis and SPICE simulations. The area on-chip and power analysis are performed and the results are compared with conventional CMOS logic and threshold logic-based magnitude comparator. The feasibility of the proposed design is analyzed using LTSPICE and simulation results show an average power consumption of $39.92\mu \mathrm{W}$ and 32.14% improvement in the area compared to resistive threshold logic (RTL).

I. Introduction

Nowadays, due to increase in the usage of portable consumer electronics, low power designs become crucial. The market demand for chip design concentrates mainly on (i) Low power (ii) High speed (iii) Less area on-chip. Intensified research proves that memristors are one of the promising alternate solutions for nearing obsolesce of CMOS technology [1]. The binary comparator plays a major role in multiprocessing and parallel computing. In traditional CMOS method, the logic function is implemented using both PMOS and NMOS transistors, but the application of large number of inputs results in circuit complexity and degraded operating speed. Even though, the CMOS technology leads to the innovation of several logic design styles like Pass Transistor Logic (PTL), Pseudo NMOS logic style and Transmission Gates, the use of MOSFET is nearing its obsolence. A memristor is a nonvolatile, 2-terminal nano sized alternative device for MOSFET with unique characteristics of computing and storing simultaneously for unconventional computational framework. The logic styles based on memristors like IMPLY logic, RTL [2] and MRL etc., is explored for the implementation of digital logic circuits. The proposed 2-bit comparator is designed based on hybrid CMOS-memristive logic based on MRL. The idea of hybrid CMOS-memristive logic based on Memristor Ratioed Logic (MRL) [3] implements AND and OR gates with only memristors, but NOT gate requires CMOS inverter. In MRL, the logic value is represented as voltage, whereas memristance is represented as logic value in IMPLY logic.