本論文介紹提出的冷啟動晶片以及能量收集系統。其中，冷啟動晶片的開發是為了整合進入能量收集系統而做的準備，該晶片本身的目的是將極低的輸入電壓轉換成高輸出電壓。而提出的能量收集系統採用雙輸入、單電感器和多輸出之降壓-升壓轉換器，旨在最大限度地從熱電產生器中提取能量並轉換成常見的1.2V、1.8V和3.3V三種不同電壓準位供負載使用，其中，雙輸入是指能量收集模式以熱電產生器為輸入能源，能量再利用模式則改為使用超級電容器作為輸入能源。

所提出的系統有三種操作模式：冷啟動模式、能量收集模式和能量再利用模式。在冷啟動模式下，熱電產生器電壓被抬升到1V並儲存在啟動電容中，該電容在模式剛切換成能量收集模式的瞬間提供電路所需的電壓。量測結果顯示，在熱電產生器電壓為200mV的情下，1μF的啟動電容器可在187ms內充電至1V。在能量收集模式下，降壓-升壓轉換器使用非同步控制以邊界導通模式運作。峰值電感電流控制部分開路電壓最大功率點追蹤排除了輸入電壓變化的影響，並調節電感電流以追蹤最大功率點。自適應雙向誤差電壓校準零電流開關器調整比較器誤差電壓以最大限度地減少反向電流損耗，從而提高整體效率。在能量再利用模式下，轉換器切換成使用超級電容器作為輸入能源，確保系統在低輸入功率的條件下依舊能保持運作。所提出的雙輸出動態感測脈衝跳頻模式減少了轉換器的開關損耗，並可以將剩餘雙輸出穩壓在其指定電壓上。

提出的能量收集系統採用0.18μm 1P6M混合信號CMOS製程製造，所耗面積為7.65mm^2。由量測結果可知，在輸入能量為2mW之峰值效率可達83.9%。

This thesis introduces the proposed cold start-up chip and the energy harvesting system. The development of the cold start-up chip is aimed at preparing for its integration into the energy harvesting system. The primary purpose of the cold start-up chip is to convert extremely low input voltages into high output voltages. On the other hand, the proposed energy harvesting system adopts a dual-input, single-inductor, and multi-output buck-boost converter. Its objective is to maximize energy extraction from thermoelectric generators (TEG) and convert it into three common voltage levels (1.2V, 1.8V, and 3.3V). In addition, dual input refers to the energy harvesting mode using a thermoelectric generator as the input source, while the energy reuse mode switches to using a supercapacitor as the input source.

The system operates in three modes: cold start-up mode, energy harvesting mode, and energy reuse mode. In the cold start-up mode, the voltage from the TEG is boosted to 1V and stored in a start-up capacitor. This capacitor provides the required voltage to the circuit when transitioning into the energy harvesting mode. Measurement results show that with a TEG voltage of 200mV, a 1μF star-tup capacitor can charge to 1V within 187ms. In the energy harvesting mode, the buck-boost converter operates in asynchronous control with boundary conduction mode (BCM). The peak inductor current control circuit, with FOCV-MPPT, mitigates the impact of input voltage variations and adjusts the inductor current to track the maximum power point. The adaptive bidirectional offset voltage calibration zero-current switch (ABOVC-ZCS) adjusts the comparator offset voltage to minimize reverse current losses, thereby enhancing overall efficiency. In the energy reuse mode, the converter switches to using a supercapacitor as the input energy source. This ensures the system continues to operate under low input power conditions. The proposed dual-output dynamic sensing pulse skip mode (DS-PSM) reduces switch losses in the converter and regulates the remaining dual output voltages to their specified levels.

The proposed energy harvesting system is fabricated using a 0.18μm 1P6M mixed-signal CMOS process, with an area of 7.65mm^2. Measurement results indicate that the peak efficiency can reach 83.9% with an input power of 2mW.

[1] S. Bose and M. L. Johnston, “A stacked-inverter ring oscillator for 50mv fullyintegrated cold-start of energy harvesters,” IEEE Proceedings of the International Symposium on Circuits and Systems, 2018.
[2] S. L. C. M. D. Ker and C. S. Tsai, “Design of charge pump circuit with consideration of gate-oxide reliability in low-voltage cmos processes,” IEEE Journal of Solid–State Circuits, vol. 41, no. 5, pp. 1100 – 1107, 2006.
[3] H. W. T. Y. H. Weng and M. D. Ker, “Design of charge pump circuit in low-voltage cmos process with suppressed return-back leakage current,” 2010 IEEE International Conference on Integrated Circuit Design and Technology, 2010.
[4] T. A. S. Bose and M. L. Johnston, “Integrated cold start of a boost converter at 57 mv using cross-coupled complementary charge pumps and ultra-low-voltage ring oscillator,” IEEE Journal of Solid–State Circuits, vol. 54, no. 10, pp. 2867 – 2878, 2019.
[5] M. M. J. Lazzaro, S. Ryckebusch and C. A. Mead, “Winner-take-all networks of o(n) complexity,” pp. 703 – 711, 1989.
[6] Z. J. Lo et al., “A reconfigurable differential-to-single-ended autonomous current adaptation buffer amplifier suitable for biomedical applications,” IEEE Transactions on Biomedical Circuits and Systems, vol. 15, no. 6, pp. 1405 – 1418, 2021.
[7] F. Reverter, “A tutorial on thermal sensors in the 200th anniversary of the seebeck effect,” IEEE Sensors Journal, vol. 21, no. 20, pp. 22122 – 22132, 2021.
[8] S. Siouane, S. Jovanovi´c, and P. Poure, “Identification of thermal resistances of thermoelectric modules by electrical characterization,” 2016 IEEE 16th International Conference on Environment and Electrical Engineering, 2016.
[9] C. L. Wei, C. H. Wu, L. Y. Wu, and M. H. Shih, “An integrated step-up/step-down dc–dc converter implemented with switched-capacitor circuits,” IEEE Transactions on Circuits and Systems II: Express Briefs, vol. 57, no. 10, pp. 813 – 817, 2010.
[10] H. S. K. Y. S. Noh, J. I. Seo and S. G. Lee, “A reconfigurable dc-dc converter for maximum thermoelectric energy harvesting in a battery-powered duty-cycling wireless sensor node,” IEEE Journal of Solid–State Circuits, vol. 57, no. 9, pp. 2719 – 2730, 2022.
[11] H. Y. L. Q. Kuai and P. K. T. Mok, “A dual-frequency thermal energy harvesting interface with real-time-calculation zcd,” IEEE Journal of Solid–State Circuits, vol. 56, no. 9, pp. 2736 – 2747, 2021.
[12] I. P. et al., “A thermoelectric energy-harvesting interface with dual-conversion reconfigurable dc–dc converter and instantaneous linear extrapolation mppt method,” IEEE Journal of Solid–State Circuits, vol. 58, no. 6, pp. 1706 – 1718, 2023.
[13] a. A. P. C. Y. K. Ramadass, “A battery-less thermoelectric energy harvesting interface circuit with 35 mv startup voltage,” IEEE Journal of Solid–State Circuits, vol. 46, no. 1, pp. 333 – 341, 2011.
[14] J.-P. I. et al., “A 40 mv transformer-reuse self-startup boost converter with mppt control for thermoelectric energy harvesting,” IEEE Journal of Solid–State Circuits, vol. 47, no. 12, pp. 3055 – 3067, 2012.
[15] T. T.-D. et al., “Power management ic with a three-phase cold self-start for thermoelectric generators,” IEEE Transactions on Circuits and Systems I Fundamental Theory and Applications, vol. 68, no. 1, pp. 103 – 113, 2021.
[16] Z. L. et al., “A sub-10 mv power converter with fully integrated self-start, mppt, and zcs control for thermoelectric energy harvesting,” IEEE Transactions on Circuits and Systems I Fundamental Theory and Applications, vol. 65, no. 5, pp. 1744 – 1757, 2018.
[17] T. A. S. Bose and M. L. Johnston, “A 3.5-mv input single-inductor self-starting boost converter with loss-aware mppt for efficient autonomous body-heat energy harvesting,” IEEE Journal of Solid–State Circuits, vol. 56, no. 6, pp. 1837 – 1848, 2021.
[18] T. Esram and P. L.Chapman, “Comparison of photovoltaic array maximum power point tracking techniques,” IEEE Transactions on Energy Conversion, vol. 22, no. 2, pp. 439 – 449, 2007.
[19] H. K. et al., “An energy-efficient fast maximum power point tracking circuit in an 800-μw photovoltaic energy harvester,” IEEE Transactions on Power Electronics, vol. 28, no. 6, pp. 2927 – 2935, 2013.
[20] Y.-C. H. A. A. Abdelmoaty, M. Al-Shyoukh and A. A. Fayed, “A mppt circuit with 25 μw power consumption and 99.7IEEE Transactions on Circuits and Systems I Fundamental Theory and Applications, vol. 64, no. 2, pp. 272 – 282, 2017.
[21] T. H. Tsai and K. Chen, “A 3.4mw photovoltaic energy-harvesting charger with integrated maximum power point tracking and battery management,” IEEE International Solid-State Circuits Conference, pp. 72 – 73, 2013.
[22] Z. C. S. H. T. G. Yu, K. W. R. Chew and L. Siek, “A 400 nw single–inductor dualinput–tri–output dc–dc buck–boost converter with maximum power point tracking for indoor photovoltaic energy harvesting,” IEEE Transactions on Power Electronics, vol. 50, no. 11, pp. 2758 – 2772, 2015.
[23] Jian-Zhou Yan; Wei-Han Pan; Hung-Hsien Wu; Tien Hsu; Chia-Ling Wei, “Photovoltaic energy harvesting chip with p & o maximum power point tracking circuit and novel pulse-based multiplier,” IEEE Transactions on Power Electronics, vol. 36, no. 11, pp. 12867 – 12876, 2021.
[24] S. Uprety and H. Lee, “A 93with irradiance-aware auto-reconfigurable mppt scheme achieving >95efficiency across 650μw to 1w and 2.9ms focv mppt transient time,” IEEE International Solid-State Circuits Conference, pp. 378 – 379, 2017.
[25] S. Uprety and H. Lee, “A 0.65-mw-to-1-w photovoltaic energy harvester with irradiance-aware auto-configurable hybrid mppt achieving >95and 2.9-ms focv transient time,” IEEE Journal of Solid–State Circuits, pp. 1827 – 1836, 2020.
[26] T. E. et al., “Dynamic maximum power point tracking of photovoltaic arrays using ripple correlation control,” IEEE Transactions on Power Electronics, vol. 21, no. 5, pp. 1282 – 1291, 2006.
[27] A. H. T. et al., “A biofuel-cell-based energy harvester with 86efficiency and 0.25-v minimum input voltage using source-adaptive mppt,” IEEE Journal of Solid–State Circuits, vol. 56, no. 6, pp. 715 – 728, 2021.
[28] H. C. C. P. H. Chen and C. L. Lo, “A single-inductor triple-source quad-mode energy harvesting interface with automatic source selection and reversely polarized energy recycling,” IEEE Journal of Solid–State Circuits, vol. 54, no. 10, pp. 2671 – 2679, 2019.
[29] H. K. et al., “A 90.2multi-output energy harvesting interface with double-conversion rejection technique and buck-based dual-conversion mode,” IEEE Journal of Solid–State Circuits, vol. 56, no. 3, pp. 961 – 971, 2021.
[30] Q. W. Q. Kuai, H. Y. Leung and P. K. T. Mok, “A high-efficiency dual-polarity thermoelectric energy-harvesting interface circuit with cold startup and fast-searching zcd,” IEEE Journal of Solid–State Circuits, vol. 57, no. 6, pp. 1899 – 1912, 2022.
[31] P. T. et al., “Comparative study of fuel-cell vehicle hybridization with battery or supercapacitor storage device,” vol. 58, no. 8, pp. 3892 – 3904, 2009.
[32] A. Paidimarri, A. P. Chandrakasan, “A wide dynamic range buck converter with subnw quiescent power,” IEEE Journal of Solid–State Circuits, vol. 52, no. 12, pp. 3119 – 3131, 2017.
[33] Frederik Dostal, “New advances in energy harvesting power conversion,” Analog Dialogue, vol. 49, no. 09, 2015.
[34] CUI Devices, CP081 030-M, PELTIER MODULE. https://www.cuidevices.com/product/resource/cp08-m.pdf.
[35] D. B. M. Seok, G. Kim and D. Sylvester, “A portable 2-transistor picowatt
temperature-compensated voltage reference operating at 0.5 vt,” IEEE Journal of Solid–State Circuits, vol. 47, no. 10, pp. 2534 – 2545, 2016.
[36] L. C. et al., “A simple smooth transition technique for the noninverting buck–boost converter,” IEEE Transactions on Power Electronics, vol. 33, no. 6, pp. 4906 – 4915, 2018.
[37] TOSHIBA, Overcurrent protection function and reverse current prevention function of the load switch IC. https://toshiba.semicon-storage.com/info/docget.jsp?did=68579.
[38] Texa Instroment, TPS61175, 3A, 40V High Voltage Boost Converter with Soft-start and Programmable Switching Frequency, 12 2008.