一個使用靈敏飛輪電流控制以改善暫態響應的單電感多輸出直流-直流轉換器

Abstract

在可穿戴設備興起的背景下，笨重的被動元件依舊是在實現最小化電源管理IC這一目標中的瓶頸。單電感多輸出直流-直流轉換器透過使用單個電感來生成多輸出電壓級而成為一個可行的解決方案。然而，單電感多輸出直流-直流轉換器中的交互調節問題不可避免的威脅到系統的可靠性。現有的解決方案透過精確計算輸入和輸出之間的能量差來減少交互調節，但往往導致系統複雜性增加。其設計關鍵挑戰在於如何在最小化面積的同時，保持直流-直流轉換器的可靠性。 本論文提出了一種使用快速調變飛輪電流控制的單電感多輸出直流-直流轉換器用以增強暫態響應。主要設計目標為顯著減少控制電路的面積大小以及複雜度，同時又能最大化單電感多輸出直流-直流轉換器的優勢。此外，透過使用變頻控制，系統得以更快速的因應輸出負載變化，有效減少交互調節現象。 此晶片透過台積電0.18μm 1P6M High Voltage Mixed Signal CMOS製程實現。量測結果證實，該轉換器能在動態負載條件下穩定調節三個不同的輸出電壓，分別為2.2伏、1.8伏和1.2伏。轉換器的峰值效率達到85.87%，並可提供最高達850mW的總輸出功率。透過應用靈敏飛輪電流控制和變頻控制技術，轉換器具備快速的暫態響應，有效減少電壓偏差和在負載突變達到250毫安培時的穩定時間。所提出的單電感多輸出直流-直流轉換器在優化功率密度和效率的同時，確保了系統的穩定性和可靠性。

The bulky passive components remain a bottleneck in achieving the goal of minimizing power management ICs, especially with the rise of wearable devices. Single-Inductor Multiple-Output (SIMO) DC-DC converters offer a suitable solution by using a single inductor to generate multiple output voltage levels. However, the cross-regulation issues inevitably threaten the system's reliability. Existing solutions minimize cross-regulation by precisely calculating the input-output energy difference, but they often lead to increased system complexity. The design challenge lies in achieving a balance between minimizing area cost and maintaining the reliability of DC-DC converters. This thesis proposes a SIMO converter using Responsive Freewheeling Current Control (RFCC) for transient response enhancement. The design aims to reduce the complexity and size of the control circuitry significantly while maximizing the benefits of SIMO converters. Additionally, by applying variable frequency control, the system can respond more quickly to changes in output load, effectively reducing the cross-regulation phenomenon. This chip was implemented using the TSMC 0.18μm 1P6M High Voltage Mixed Signal CMOS process. Measurement results confirm the converter’s capability to regulate three distinct output voltages, 2.2V, 1.8V, and 1.2V, under dynamic load conditions. The converter achieves a peak efficiency of 85.87% and delivers a total output power of up to 850 mW. The application of Responsive Freewheeling Current Control (RFCC) and variable frequency control contributes to a swift transient response, significantly reducing voltage deviations and settling times during load transient up to 250mA. The proposed SIMO converter optimizes power density and efficiency while maintaining system stability and reliability.