A Hybrid PTL-TGL 4:1 Multiplexer with MTCMOS Power Gating for Energy-Efficient VLSI Systems

Abstract

The increasing impact of power dissipation and leakage current in deep-submicron CMOS technologies has become a major challenge in the design of portable and battery-powered VLSI systems. This paper presents the design and optimization of a 4:1 multiplexer based on a hybrid Pass Transistor Logic (PTL) and Transmission Gate Logic (TGL) architecture integrated with the Multi-Threshold CMOS (MTCMOS) power-gating technique to improve energy efficiency. In the proposed design, PTL is employed to reduce the transistor count and propagation delay, while TGL is incorporated to ensure full voltage swing and maintain reliable signal transmission. To further reduce standby power consumption, a high-threshold sleep transistor is introduced through the MTCMOS technique, enabling effective isolation of the logic circuit from the power supply during inactive operation. The proposed architecture is designed and simulated using Tanner EDA tools with 90 nm CMOS technology. Simulation results demonstrate a significant reduction in leakage power while introducing only a minimal delay overhead compared with conventional 4:1 multiplexer designs. The combined advantages of hybrid PTL–TGL logic and MTCMOS power gating provide an effective balance between power efficiency and circuit performance, making the proposed architecture a suitable solution for modern low-power and high-speed VLSI applications.

Introduction

The text presents a study on designing and evaluating a low-power 4:1 multiplexer for VLSI applications using advanced logic techniques. With the increasing demand for energy-efficient electronic systems, optimizing power consumption, delay, and area has become essential. The work focuses on comparing different logic styles such as Conventional CMOS, Gate Diffusion Input (GDI), Pass Transistor Logic (PTL), and Transmission Gate Logic (TGL) to identify efficient circuit architectures.

The literature review highlights that GDI and PTL reduce transistor count, area, and power consumption, while Transmission Gate Logic improves signal integrity and provides full voltage swing. However, traditional approaches often face limitations such as threshold voltage loss, increased complexity, and insufficient analysis under practical conditions like process variations. The study addresses these challenges by proposing a Hybrid PTL–TGL based 4:1 multiplexer integrated with Multi-Threshold CMOS (MTCMOS) power gating.

The proposed design combines the advantages of PTL and TGL: PTL minimizes switching capacitance and transistor count, while TGL improves reliability by eliminating voltage degradation. MTCMOS technology is incorporated using a high-threshold sleep transistor to reduce leakage power during standby operation without affecting normal functionality.

The design is implemented using Tanner EDA tools with 90 nm CMOS technology. The methodology includes logic design, hybrid circuit development, MTCMOS integration, schematic creation in S-Edit, simulation using T-Spice, and performance evaluation. The multiplexer is analyzed using parameters such as:

• Average power consumption
• Leakage power
• Propagation delay
• Power-Delay Product (PDP)

Simulation results demonstrate that the proposed hybrid architecture provides:

• Reduced dynamic and leakage power consumption
• Lower transistor complexity
• Improved signal transmission quality
• Better balance between speed and energy efficiency

Conclusion

The proposed Hybrid 4:1 multiplexer provides a balanced improvement in power, delay, and area compared to Conventional CMOS and GDI designs. While CMOS ensures reliable operation, it has higher power consumption, and GDI may experience signal degradation. Although hybrid logic can introduce voltage loss and reduced noise margins, careful design minimizes these effects, making it an efficient solution for low-power VLSI applications.

References

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Copyright

Copyright © 2026 P. Vasavi, Dr. G. Sujatha. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.