Highly Energy-Efficient and Small-Area Single-Bit Approximate GDI-Based Subtractor for Dividers' Implementation

Subject Areas : Electronic Engineering

Fatemeh Pooladi ¹ (Department of Electrical Engineering, Shiraz Branch, Islamic Azad University, Shiraz, Iran)
Farshad Pesaran ² (Islamic Azad University, Shiraz Branch)
nabiallah شیری ³ (استاد دانشکاه آزاد شیراز-صدرا)

Received: 2023-11-01 Accepted : 2023-12-22 Published : 2024-02-08

Keywords: Subtractor, divider, approximate calculations, carbon nanotube.,

Abstract :

In digital circuits that have a high number of transistors, energy dissipation is still a challenge. New techniques like approximate computing are somehow helpful for challenge solving. Therefore, three new single-bit subtractors are presented based on the approximate computing and gate diffusion input (GDI) technique. Compared to the literature, proposed circuits 1-3 with different truth tables have 10, 8, and 6 transistors, respectively, which causes a significant reduction in power consumption. The simulation results based on the carbon nanotube field effect transistor (CNTFET) technology with a channel length of 32 nm confirmed the superiority of the circuits. The proposed circuit 3 with no inverter has the best circuitry performance. However, due to the presence of 4 errors in this circuit, its error rate is higher compared to other circuits. Examining the effects of changes in the voltage source, the fan-outs, and the process-voltage-temperature (PVT) variations showed a superior energy performance of the proposed circuit 3. Also, by embedding the proposed circuits in the 8-bit divider structure, the superiority of the proposed circuit 3 in terms of various figures of merits was observable by at least 50%.

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