A 20~20 KHz Active Rectifier with Adaptive Delay Time Control and 1000X Frequency Detecting Techniques for Acoustic Wave Energy Harvesting

In this paper, a wide frequency range active rectifier for acoustic wave energy harvesting is proposed, which can operate in a frequency range of 20-20 KHz. The two PMOS switches are driving with cross-coupled connection, and the NOMS switches are designed as active-diodes. Adaptive delay time control technique as the loop control method is applied to regulate the conduction period time of the NMOS. In order to realize precise period time control under extremely frequency range, the gate signals (VGNA, VGNB) of the NMOS are generated mainly by switching the capacitor and the current (ION, IOFF), so that the NMOS can be turned on and off on time. The active rectifier is implementation by using standard 0.18 μm CMOS process. Simulated results show that its total power consumption is 13.5 μW at steady stage when the input frequency is 2 KHz and load resistance is 10 KΩ, the output power is up to 602 μW, and the PCE reaches 97.8%.