Power Management Unit for Photovoltaic Energy Harvesting

本篇論文提出一個針對光電能源截取，及電池的低功耗單電感雙輸出之直流轉直流升壓轉換器。其中提出的前饋控制，能夠精準地調節佔空比且不需任何補償，而研究中的啟動機制能夠縮減開機時間至一百毫秒以內。此外，偽連續導通模式及自動基板電位選取電路也被應用於此轉換器中。以上的特性能夠減少對外部原件的多餘需求及成本，並且能有效地增加整體電路效率及穩定性等表現。此電路在量測上可達到74%的轉換效率、開機時間為30毫秒，且晶片面積只有1.5×1.5 mm2的大小。除此之外，此篇論文也提出一低功耗且操作於突發模式的直流轉直流降壓轉換器，及一個低壓差穩壓器搭配增益提升誤差放大器。上述這些電路架構，能夠將鋰電池充電至4.2伏特，並且同時提供一穩定的1.8伏特電壓源供訊號處理電路使用。結合這些電路設計，一個應用於光電能源截取之電源管理單元即可完成。 另一方面，為提供此電源管理單元一個穩定的參考電壓，此篇論文也提出了一個超低功耗的能隙參考電路。其中提出的參考電流和正比絕對溫度電壓產生器，能夠偕同產生一個不受溫度、電源電壓、製程所影響的1.276伏特參考電壓，且所耗功率僅有206毫微瓦特。 此晶片是以聯華電子公司零點一八微米互補式金氧半製來實現，操作電壓為1.8伏特至4.2伏特，切換頻率為100 KHz，而其他更為詳細的設計技術以及量測方式則詳見本篇論文。An on-chip low power single-inductor dual-output (SIDO) DC-DC boost converter was proposed for battery and photovoltaic energy harvesters. The proposed feed-forward control regulates the duty cycle (TON/TOFF) accurately without any compensation, and the start-up mechanism could shorten the start-up time under 100 milliseconds. Furthermore, the pseudo continuous conduction mode and the automatic body selector were also applied to this converter. These features could reduce excessive requirements and the cost of external components, which increases the performance such as higher efficiency and greater stability. The measurement result of the chip could achieve an efficiency of 74% and a start-up time of 30 ms with a small area size of simply 1.5×1.5 mm2. In addition, a low power burst mode DC-DC buck converter and a low dropout regulator with gain boosting error amplifier were also proposed. These building blocks could provide a supply voltage of 1.8V for some signal processing circuits and charge the Li-ion battery to 4.2V. As a result, a power management unit for photovoltaic energy harvesting was presented. Besides, an ultra-low power bandgap reference was proposed to provide a robust voltage reference to PMU. The proposed proportional to absolute temperature (PTAT) generator and the current reference could generates a reference voltage of 1.276 V, which is independent of the temperature, power supply, and process technology and its power consumption is simply 206 nW. The chip is implemented by UMC 1P6M 0.18μm process technology. The range of the operation voltage is from 1.8V to 4.2V, and switching frequency is 100 KHz. The other detailed techniques and measurements was included in this thesis, too