A Ten-Level Series-Capacitor 24-to-1-V DC–DC Converter With Fast In Situ Efficiency Tracking, Power-FET Code Roaming, and Switch Node

Abstract

This work presents a high-efficiency ten-level series- capacitor 24-to-1-V buck converter with three techniques to improve its efficiency and reliability. First, we propose a fast in situ efficiency tracking (FIT) technique to maximize efficiency across load conditions and process, voltage, and temperature (PVT) variations. The second technique is the power-FET code roaming technique. It distributes the stress on power-FET segments at light load conditions to avoid excessive aging on specific segments. Last but not least, we directly supply the gate drive voltage from converter switch nodes to save power and area. The proposed converter was fabricated in a 180-nm BCD process. It achieves a peak power efficiency of 93.89% at 405-mA load current. The proposed fast in situ tracking technique demonstrates an efficiency improvement of up to 34.74% compared to the baseline without efficiency tracking. It also increases the high-efficiency (>85%) load range from 13.51× to 76.92×. Besides, the power-FET roaming technique mitigates the development of local hotspots, thus slowing down the ON-time resistance degradation by 5.8×.