This paper presents a novel self-powered and fully autonomous interface circuit to extract piezoelectric energy from vibrations available in the environment for supplying DC voltage to electronic loads. A new energy extraction technique called Synchronized Switch Harvesting on Capacitor-Inductor (SSHCI) is utilized, which reduces system cost through a downsized inductor in the range of tens of mu H's. while achieving as high voltage flipping efficiency as cony entional SSHI circuits. Fabricated in 180 um standard CMOS technology, the interface circuit has been tested on a MEMS piezoelectric energy harvester with 2 nF intrinsic capacitance in presence of vibrations at 415 Hz resonant frequency. SSHCI circuit provides 6.14x relative irnprov ement over/maximum output power of an ideal full-bridge rectifier (FBR) by utilizing a 68 mu H inductor to charge a 453 nF storage capacitance. A maximum power conversion efficiency of 901% has been measured for SSHCI operation due to low power design techniques and optimized switching time for charge flipping.