Power Management Unit for Photovoltaic Energy Harvesting

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.