應用於低負載處理器之交換式電容直流電壓轉換器之設計與實作

Design and Implementation of Switched-Capacitor DC-DC Converter for Light-load Processor

胡睿霖(Rui-Lin Hu)

指導教授 ： 劉宗德

國立臺灣大學/電機資訊學院/電子工程學研究所/碩士(2018年)

https://doi.org/10.6342/NTU201800638

摘要

交換式電容電壓轉換器(Switched-Capacitor Voltage Regulator,SCVR)，優點在於高轉換效率與可以全部電路積體化(Fully Integrated)，不需要使用外部元件，即可達到電壓轉換的效果，非常適合運用在物聯網(Internet of Things,IOT)的產品，這些產品需要不同的工作電壓，所需要的工作負載也不盡相同，因此本論文希望提出一種可以於低負載(Low loading)工作模式處理器應用之交換式電容電壓轉換器，並且可以提供高轉換效率。

首先本論文會分析交換式電容電壓轉換器的基本操作原理，並分析基本2:1的交換式電容電壓轉換器的功率損耗與電路元件設計的關連性，去找出當電路在不同負載的時候，要改變什麼電路元件參數，可以得到最好的結果，並探討現有的改善方法，分析其優缺點，最後以電路迴授控制(Feedback control)的方法來修改操作頻率來讓電路工作在好的工作點，以維持高效率。

本論文提出的交換式電容電壓轉換器，可以有效改善在低負載工作模式時的效率，當負載改變時，電路最佳工作點會偏移，利用迴授控制(Feedback control)，可令電路工作於較好的工作點，並且透過TSMC 0.18um製程晶片實作，來驗證本論文提出的方法是否可行，而本論文的設計概念可以有效修正當負載變動時而導致效率降低的情形。

關鍵字

交換式電容電壓轉換器 ； 迴授控制 ； 高效率 ； 輕載 ； 動態比較器

並列摘要

The advantages of Switched-Capacitor Voltage Regulator (SCVR) are the high conversion efficiency and the ability to be fully integrated without external components. Therefore, the SCVR is applicable to be integrated in IoT (Internet of Things) products. These products need different operating voltages, and their working loads vary. Thus, this thesis intends to propose a SCVR, which can be used in the processor under low-loading mode and provide high conversion efficiency.
This thesis first analyzes the basic theory of how the SCVR works. Then, the design parameters related to power efficiency loss of basic 2:1 SCVR are discussed. In order to obtain the best efficiency result, this thesis tried to find out which parameter of the electronic components should be properly changed under different working loads of circuit, and looked into the pros and cons of the existing designs. Finally, to make the circuit function on a favorable operating point and remain highly efficient, the proposed solution is to modify the operating frequency by feedback control method.

The SCVR presented by this thesis can effectively enhance the efficiency of processor under low-loading mode. When the working load change, the best operating point of circuit deviates. The proposed feedback control method can make circuit function on a better operating point. The proposed solution is verified by TSMC 0.18µm CMOS designs. The design concept can significantly improve the efficiency dropping caused by the load change.

並列關鍵字

Switched-capacitor Voltage Regulator (SCVR) ； Feedback control ； High efficiency ； light-load ； Dynamic Comparator

參考文獻

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[2] S. S. Kudva and R. Harjani, "Fully Integrated Capacitive DC–DC Converter With All-Digital Ripple Mitigation Technique," in IEEE Journal of Solid-State Circuits, vol. 48, no. 8, pp. 1910-1920, Aug. 2013.

[3] N. Butzen and M. Steyaert, "12.2 A 94.6%-efficiency fully integrated switched-capacitor DC-DC converter in baseline 40nm CMOS using scalable parasitic charge redistribution," 2016 IEEE International Solid-State Circuits Conference (ISSCC), San Francisco, CA, 2016, pp. 220-221.

[4] D. Kilani, M. Alhawari, B. Mohammad, H. Saleh and M. Ismail, "An Efficient Switched-Capacitor DC-DC Buck Converter for Self-Powered Wearable Electronics," in IEEE Transactions on Circuits and Systems I: Regular Papers, vol. 63, no. 10, pp. 1557-1566, Oct. 2016.

[5] C. K. Teh and A. Suzuki, "12.3 A 2-output step-up/step-down switched-capacitor DC-DC converter with 95.8% peak efficiency and 0.85-to-3.6V input voltage range," 2016 IEEE International Solid-State Circuits Conference (ISSCC), San Francisco, CA, 2016, pp. 222-223.