A PVDF-film Energy Harvesting Circuit Using 40-nm CMOS Process

This paper presents an energy harvest circuit design integrated with piezoelectric devices made of polyvinylidene fluoride (PVDF) films. The piezoelectric devices will be used in wearable electronics, e.g., insole and clothes, to prevent child or elderly missing. The proposed design consists of a low-voltage piezoelectric energy harvest circuit, PVDF films and discretes, which will be integrated with Bluetooth low-energy (BLE) Tx/Rx. Therefore, when the kid or elder is out of a pre-defined distance, the missing beacon via Bluetooth devices will alarm to the family so take actions. The harvest circuit is realized using TSMC 40nm CMOS process, wherein the proposed 2-stage stepping-up architecture boosts the generated from 120 mV to 1 V. Since the output of PVDF film is an AC signal, an AC/DC converter based on a voltage multiplier not only carries out AC/DC conversion, but also elevate the DC voltage to 0.26 V, which is then through boosted by DC/DC converter to 1 V. The all-PVT-corner post-layout simulations demonstrate the worst output power is 4.2 mW, which is more than enough to drive a low-power wireless frontend, e.g. Bluetooth lower energy (BLE) Tx/Rx.