Highly Efficient Cmos Integrated Interface Circuit for High Voltage Piezoelectric Generators

This work presents a CMOS integrated interface circuit (IIC) enabling highly efficient energy transfer from piezoelectric generators (PGs) to a storage element, e.g. a large capacitor. Due to the low power consumption of 4.7 μW assuming a supply voltage of 2.5 V, the IIC can be supplied totally by the storage capacitor. The storage capacitor can be passively charged via a bypassing circuit if its voltage is not sufficient to supply the control circuit. PG voltage amplitudes of up to 18 V are tolerated by using special high voltage transistors. Using an improved switching technique, simulations suggest an efficiency gain of about 8 % compared to a formerly-used switching technique, resulting in an efficiency between 80 % and 90 % for PG voltage amplitudes higher than 6 V.