Device-Circuit Interaction and Performance Benchmarking of Tunnel Transistor-Based Ex-OR Gates for Energy Efficient Computing

摘要

This paper explores the design and analysis of 20nm tunnel transistor-based Exclusive-OR (Ex-OR) gates and half-adder cells with circuit interaction (co-design) approach for energy efficient and reliable computing architectures at scaled supply voltages (50-300mV). TFETs have attracted much attention recently for energy efficient system designs. The circuit interaction is made possible for designing more consistent functional architectures at the minimum power supply of 50-300mV. Using this technique, the core computational blocks of basic adder blocks and Ex-OR gates are designed with TFET as a fundamental device and the whole design procedure is elaborated in this paper. The primary classifications of Tunnel FETs, viz. Homo-junction TFET (HoJn TFET) and Hetero-junction TFETs (HeJn TFET) are investigated thoroughly under different constraints specifically at the device configurations. By considering the above-mentioned subtypes of TFETs, three variants of Ex-OR primitive gates are modeled and are named with respect to the use of transistors as static complementary TFET-12T (SC12T), Transmission Gate logic-8T (TG8T) and Improved Transmission Gate logic-6T (ITG6T) Ex-OR gate designs. The benchmarking of the proposed gates is done using double-gate Si FinFET at 20nm technology. Amongst all the three proposed Ex-OR designs of SC12T, TG8T and ITG6T in addition to that of LVT and HVT FinFET/CMOS, only ITG6T is the designer's choice by offering the minimum power consumption as well as high energy, improved choice compared to the other two styles of designs and also when robustness and reliability are taken into account, SC12T and TG8T designs are not providing the full swing of outputs. The minute glitch with that of ITG6T designs is a lesser reliability feature and for this the best alternative is TFET TG8T by providing suppressed over shoots and enhanced transition speed. From the performed multi simulations under different critical conditions and at supply voltage of 100mV, it is being demonstrated that the energy efficient circuit option is the SC12T and ITG6T Ex-OR designs which are validated with the steep slope characteristics of TFET's and also these two designs offer reliability advantage. The major restrictions from the energy efficiency issues are eliminated and disclosed in the HoJn TFETs and HeJn TFET by using circuit co-design methodology and TFETs steep slope characteristics.