Power Delivery for High-Performance Microprocessors—Challenges, Solutions, and Future Trends
Kaladhar Radhakrishnan, Madhavan Swaminathan, Bidyut K. Bhattacharyya
Abstract
The power delivery requirements for the early microprocessors were fairly rudimentary due to the relatively low power levels. However, several decades of exponential scaling powered by Moore's law have greatly increased the power requirements and the complexity of the power delivery scheme. The breakdown in Dennard scaling in the mid-2000s has ushered in the multicore era which has increased the number of cores and the power consumption in microprocessors. The steady growth in the power levels and the number of power rails in high-performance microprocessors have increased the power delivery challenges. Integrated voltage regulators (IVRs) have emerged as a key power delivery technology to address these challenges. There are a number of IVR schemes implemented on-die ranging from the simple power gate to fully integrated switching regulators. After covering the fundamentals of power delivery, this article discusses the pros and cons of different types of IVR as well as the technology ingredients required to meet future IVR requirements. This article concludes with a section on advanced packaging technologies that are being developed and needed to enable heterogeneous integration and their impact on power delivery.