An Active Voltage Doubling Rectifier with Unbalanced-Biased Comparators for Piezoelectric Energy Harvesters

Abstract

For wearable health monitoring systems, a fundamental problem is the limited space for storing energy, which can be translated into a short operational life. In this paper, a highly efficient active voltage doubling rectifier with a wide input range for micro-piezoelectric energy harvesting systems is proposed. To obtain a higher output voltage, the Dickson charge pump topology is chosen in this design. By replacing the passive diodes with unbalanced-biased comparator-controlled active counterparts, the proposed rectifier minimizes the voltage losses along the conduction path and solves the reverse leakage problem caused by conventional comparator-controlled active diodes. To improve the rectifier input voltage sensitivity and decrease the minimum operational input voltage, two low power common-gate comparators are introduced in the proposed design. To keep the comparator from oscillating, a positive feedback loop formed by the capacitor C is added to it. Based on the SMIC 0.18-μm standard CMOS process, the proposed rectifier is simulated and implemented. The area of the whole chip is 0.91×0.97 mm 2 , while the rectifier core occupies only 13% of this area. The measured results show that the proposed rectifier can operate properly with input amplitudes ranging from 0.2 to 1.0V and with frequencies ranging from 20 to 3000 Hz. The proposed rectifier can achieve a 92.5% power conversion efficiency (PCE) with input amplitudes equal to 0.6 V at 200 Hz. The voltage conversion efficiency (VCE) is around 93% for input amplitudes greater than 0.3 V and load resistances larger than 20kΩ.

Battery voltage-balancing applications of disk-type radial mode Pb(Zr ∙ Ti)O3ceramic resonator

“…PRs are compact electro-mechanical devices that convert electrical energy to mechanical energy. [3][4][5][6] They can be produced in large numbers in a short time using automated batch fabrication process. Thus, the use of these devices allows the fabrication of the entire battery voltage-balancing circuit at a low cost using an automated process in mass production.…”

A self-powered zero-quiescent-current active rectifier for piezoelectric energy harvesting

“…A full-bridge rectifier is commonly used, but passive diodes have high forward voltage drop and small conduction angle that resulted in high power consumption and decreased efficiency in extracting energy. Hence, a rectifier with active diodes is adopted to achieve higher efficiency [3,4,5,6,7,8,9,10]. The power transistor that is driven by a comparator or an op amp of the active diode has very low forward voltage drop.…”