Hybrid start-up strategy for low voltage electromagnetic energy harvesting systems

The demand for power is increasing due to the rapid growth of the population. Therefore, energy harvesting (EH) from ambient sources has become popular. The reduction of power consumption in modern wireless systems provides a basis for the replacement of batteries with the electromagnetic energy harvesting (EMEH) approach. This study presents a general review of the EMEH techniques for autonomous sensor (ATS) applications. Electromagnetic devices show great potential when used to power such ATS technologies or convert mechanical energy to electrical energy. As its power source, this stage harvests ambient energy and features a self-starting and self-powered process without the use of batteries. Therefore, it consumes low power and is highly stable for harvesting energy from the environment with low ambient energy sources. The review highlights EMEH circuits, low power EMEH devices, power electronic converters, and controllers utilized in numerous applications, and described their impacts on energy conservation, benefits, and limitation. This study ultimately aims to suggest a smart, low-voltage electronic circuit for a low-power sensor that harvests electromagnetic energy. This review also focuses on various issues and suggestions of future EMEH for low power autonomous sensors.

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Low Voltage Delay Element with Dynamic Biasing Technique for Fully Integrated Cold-Start in Battery-Assistance DC Energy Harvesting Systems

Applied Sciences ◽

10.3390/app10196993 ◽

2020 ◽

Vol 10 (19) ◽

pp. 6993 ◽

Cited By ~ 1

Author(s):

Zushuai Xie ◽

Zhiqiang Wu ◽

Jianhui Wu

Keyword(s):

Energy Harvesting ◽

Low Voltage ◽

Cold Start ◽

The Body ◽

Ring Oscillator ◽

Cmos Process ◽

Delay Element ◽

Fully Integrated ◽

Start Up ◽

Harvesting Systems

This paper proposes an ultra-low voltage delay element for battery-assistance DC energy harvesting systems. By inserting a low voltage level shifter (VLS), a wider voltage range is obtained to bias the body of the delay element. Thus, both the voltage transfer curve (VTC) and the DC gain of the delay element are enhanced. Due to the introduction of the VLS, the cold start-up ring oscillator constituted by the proposed delay element can achieve oscillation under an extremely low input voltage. The fully integrated cold start-up ring oscillator with 21 stages of the proposed element is implemented in a standard 180 nm complementary metal oxide semiconductor (CMOS) process. The post-layout experimental results indicate that the cold start-up ring oscillator can retain oscillation when the power supply voltage (VDD) is 24 mV under a typical corner at room temperature. The output voltage swing of the cold start-up ring oscillator based on the proposed delay element is improved by more than 55% under VDD = 40 mV compared with a stacked inverter-based cold start-up ring oscillator. Monte Carlo (MC) simulation from 100 samples shows the enhanced output swing with the proposed delay element under process variation.

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