This paper presents a voltage flip technique dedicated to enhance the power performance of piezoelectric energy harvesters. The concept draws on the use of a fraction of the stored charge to efficiently flip the voltage across the piezoelectric transducer. The proposed technique, referred to as FAR (Full Active Rectifier), does not require any inductor or additional capacitor and/or complex voltage flipping control. It only needs a reduced set of switches, an active diode and a simple control sequence, and can thus be implemented on a fully integrated circuit. An interface circuit has been designed and fabricated in a 0.35-µm CMOS process. Experimental results revealed that the proposed FAR extracts 19.1 µW from an off-the-shelf piezoelectric transducer when the output voltage is regulated at 1 V with 1 V open-circuit voltage and delivers up to 20% more power than the conventional Switch-only technique under load constraint. It also shows over 11x power efficiency improvement compared to a conventional diode-based full bridge rectifier.