A High-Efficient 95.6% Rectifier With Passive AC-DC Voltage Quadrupler for Low-Frequency Electromagnetic Energy Harvesting System

This article present high efficient electromagnetic energy harvesting system for low frequency applications. The proposed circuit is composed of two stages. In the first stage electromagnetic (EM) rectifier uses an improved rectifier structure with active diodes powered internally by a passive ac-dc positive and negative voltage quadrupler. This boost input peak voltage 0.6 V to +0.8 V and -0.8 V and power internally unbalance-size comparators (Comp_1 and Comp_2). The unbalance size comparator minimize the delay by introducing input offset in order to minimize the reverse leakage current. Due to this, the efficiency is improved to 95.6% at 0.6 mA load current. The second stage is step up dc-dc converter with proposed soft start circuit and min-max duty generator circuit. The proposed soft start circuit prevent dc-dc converter circuit from inrush current. The inrush current reduce the efficiency of dc-dc converter and can drain out the battery energy. In order to avoid undesirable feedback voltage, the dc-dc converter uses a min-max duty generator. The high-side and low-side driver control signals are generated by a dead-time generator to avoid the high-side and low-side power switches operating simultaneously. The step-up converter is designed by using 130 nm CMOS technology. The input voltage of dc-dc is the output of EM rectifier, which is 1V and output voltage is 1.3V at 0.5mA load current. The efficiency of step-up dc-dc converter is 94.2% and the system efficiency is 90% at 10 Hz frequency.