Implementation of Boolean Functions Using Tunnel Field-Effect Transistors

S Garg,Sneh Saurabh

doi:10.1109/jxcdc.2020.3038073

Abstract

Tunnel field-effect transistors (TFETs) are being examined as a possible replacement of MOSFETs for digital applications. However, TFETs have small ON-state current and, typically, exhibit reduced speed compared with conventional MOSFETs. Nevertheless, TFETs have some distinct characteristics that can be exploited for digital applications. In this article, using simulations, we show that a single device, in which two terminals are biased independently, can realize all primary two-input Boolean functions, such as AND, OR, NAND, NOR, XOR, and XNOR. By modifying the architecture of double-gate TFET (DGTFET) slightly and appropriately choosing device parameters, the Boolean functions AND, OR, NAND, NOR, and XNOR can be implemented. In addition, we propose a twin double-gate (TDG) TFET architecture, which can implement the inhibition functions $A'B$ and $AB'$ . By suitably combining the inhibition functions, an XOR functionality can be obtained in a single device. These implementations demonstrate that the unique characteristics of TFET, such as ambipolar conduction and dependence of tunneling on the gate–source/drain overlaps, can be exploited to realize logic functions compactly.

Highlights

C OMPLEMENTARY metal–oxide–semiconductor (CMOS) technology has been used over the past four decades to realize digital circuits since it provides excellent performance, extremely small standby power consumption, low cost, and good reliability characteristics [1]–[3]
This is due to the limitation of the subthreshold swing of the metal–oxide–semiconductor field-effect transistor (MOSFET), which cannot be lower than 60 mV/decade at room temperature [6]–[8]
The band diagrams for double-gate TFET (DGTFET) realizing AND Boolean function across the length of the device for different input combinations are shown in Fig. 8, illustrating that the band-to-band tunneling (BTBT) is enabled for the ‘‘11’’ case

Summary

INTRODUCTION

C OMPLEMENTARY metal–oxide–semiconductor (CMOS) technology has been used over the past four decades to realize digital circuits since it provides excellent performance, extremely small standby power consumption, low cost, and good reliability characteristics [1]–[3]. The threshold voltage of the transistors and the supply voltage of the digital circuits cannot be further reduced in MOSFETs without degrading the performance and the energy efficiency This is due to the limitation of the subthreshold swing of the MOSFET, which cannot be lower than 60 mV/decade at room temperature [6]–[8]. The implementation of Boolean functions, such as AND, OR, NAND, NOR, and XNOR, have been shown to be realized using a single double-gate TFET (DGTFET) requiring fewer transistors in comparison to the conventional CMOS-based implementations [18], [19]. A twin DGTFET (TDG-TFET) structure has been shown to realize the inhibition functions A B and AB Using these inhibition functions, the implementation of the DGTFET-based XOR function is demonstrated.

BASIC TERMINOLOGY AND SIMULATION MODEL

REALIZING AND AND NOR BOOLEAN FUNCTIONS USING DGTFET

REALIZING XNOR BOOLEAN FUNCTION USING DGTFET

REALIZING XOR BOOLEAN FUNCTION USING DGTFET

VIII. CONCLUSION