An Efficient and Advanced Transition Fix Strategies for Multi-Voltage Channel-Based SoCs with Power and Timing Optimization

Abstract

As the semiconductor industry advances toward lower technology nodes, the adoption of multi-voltage designs within channel-based SoC architecture presents both significant opportunities and complex challenges, particularly in the context of stringent power optimization requirements. These designs inherently introduce complex issues related to voltage domain transitions, which are critical to managing signal integrity and timing closure. Transition phenomena between voltage domains represent a major concern, directly impacting the chip’s power, performance, and area (PPA) metrics. This paper provides an in-depth analysis of transition mechanisms in multi-voltage channel-based SoC designs, identifying root causes and quantifying their effects on timing and signal integrity. It further proposes robust, practical methodologies and design techniques to mitigate transition-related issues, ensuring these solutions integrate seamlessly without compromising design integrity or chip specifications. By systematically addressing the intricacies of multi-voltage transitions in channel-based SoCs, we deliver comprehensive and efficient strategies validated through real-world implementations.

Introduction

The text examines transition (slew) challenges in multi-voltage System-on-Chip (SoC) designs, which are widely used to improve power efficiency by allowing different blocks to operate at different supply voltages. While multi-voltage architectures deliver significant power savings, they introduce complex transition issues at voltage domain boundaries that affect timing, signal integrity, and overall design reliability, especially at advanced technology nodes.

The document explains the concept of signal transition and its impact on timing and integrity, distinguishing between clock and data transitions. In ASIC designs, signal slew must remain within limits defined in standard cell libraries; violations lead to inaccurate timing analysis and potential functional failures. These issues are amplified in multi-voltage designs due to level shifters, isolation cells, and varying drive strengths across voltage domains.

Key causes of transition problems include long interconnects, weak drivers, high fanout, crosstalk, lower metal routing, PVT variations, congestion, and improper voltage-domain crossings. To address these challenges, the text outlines mitigation techniques such as buffer insertion, driver upsizing, routing critical nets on higher metal layers, fanout reduction, crosstalk control, optimized level shifter placement, and careful voltage-domain partitioning.

The role of essential multi-voltage cells—level shifters, isolation cells, and retention cells—is described, along with practical transition-fix strategies used during physical design. Several real-world scenarios illustrate how techniques like on-route buffering, creating smaller voltage islands, and buffering feedthrough signals help resolve slew violations in complex SoCs.

Conclusion

Addressing transition challenges in multi-voltage designs is critical for achieving robust and power-efficient systems. This paper bridges the gap between theoretical concepts and practical implementation by identifying the root causes of transition violations and presenting validated solutions to overcome them without performance degradation. By applying these methodologies, designers can ensure standard cells operate within their characterized .lib parameters, meet power-performance-area (PPA) targets, preserve signal integrity across voltage domains, and maintain clock quality without compromising power efficiency. As semiconductor technology continues to advance, adopting such holistic approaches is vital for the successful development and deployment of complex SoCs. Further enhancements can be made by implementing this strategy on designs with more congestion and multiple power domains.

References

[1] https://www.vlsi-expert.com/2014/01/10-ways-to-fix-setup-and-hold-violation.html [2] https://mantravlsi.blogspot.com/2014/06/max-transition-violations.html. [3] https://www.design-reuse.com/article/60758-design-rule-violation-fixing-in-timing-closure/ . [4] https://www.design-reuse.com/article/61606-transition-fixes-in-3nm-multi-voltage-soc-design/ . [5] Cadence Innovus User Guide, http://www.cadence.com . [6] https://rtldigitaldesign.blogspot.com/2021/04/vlsiexpert-transition-violation-in.html .

Copyright

Copyright © 2025 Mukul Anand, Deepak Sharma, Nikunj Tripathi. 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.