2025 Theses Doctoral

High-Voltage and Adaptive Digital Power Management IC

Wang, Zhaoqing

The rapid development of power consumption across data centers and automotive applications has catalyzed significant advancements in power delivery system architectures. Single-stage high-voltage DC-DC converters are emerging as a promising alternative to traditional two-stage designs, offering reduced power losses and enhanced efficiency. However, achieving high efficiency across wide load ranges while ensuring long-term reliability poses several challenges.

First, the high voltage stress and large conversion ratios introduced by high-voltage inputs exceed the capabilities of conventional half-bridge topologies and standard MOSFET technology. Addressing this requires innovative power stage topologies and advanced materials or technologies for power switches. Furthermore, the wide load current variability, influenced by the workload of the loaded chip, demands that converters maintain high efficiency across diverse operating conditions. Efficiency tracking techniques are essential to balance power loss components and optimize performance under varying loads. Reliability is another critical concern due to the high voltage, elevated temperatures, extended operational periods, and heavy load conditions typical of high-voltage DC-DC converters. Health monitoring circuits and control mechanisms are necessary to sense and mitigate potential risks. Additionally, most high-voltage DC-DC converters provide a single output voltage, while the connected chips often require multiple independent supply domains to optimize speed and power consumption. This calls for on-chip power management solutions, such as digital LDOs.

Chapters 2 through 5 of this thesis detail advancements in adaptive digital control to address these challenges. The first study presents a 24V-to-1V multi-level series-capacitor DC-DC converter with fast in-situ efficiency tracking and power FET code roaming, achieving up to 34.74% efficiency improvement and mitigating ON-resistance degradation by 5.8×. The second study introduces an online reliability estimation technique for ceramic capacitors, reducing estimation error by 11.4× compared to conventional offline methods. The third study demonstrates a GaN-based DC-DC converter with unified reliability and efficiency adaptive control, enhancing efficiency by 7.7% and reducing the threshold voltage degradation by 3.8×. Finally, the fourth study reviews advancements in digital LDOs over the past decade, proposes a new figure of merit, and identifies designs achieving superior transient performance.