Hybrid energy harvesting system combining multiple sources is an alternative solution to harvest energy continuously and to increase the output power to bias the electronic systems. In this work is presented a prototype for harvesting energy, which combined three different sources. It contains a piezoelectric cantilever based on Lead-Zirconate Titanate piezoelectric transducer (PZT) in order to harvest the ambient vibrations, a solar cell for sunlight and an antenna capable to harvest ambient Radio Frequency (RF) energy. The design, implementation and characterization of the circuits for signal conversion from AC to DC for the case of piezoelectric generator, and the RF to DC for the antenna are presented. The RF harvesting circuit operates at 2.4 GHz obtaining a voltage of 71mV. The prototype is capable to generate a maximum DC power around 241.3 mW when the piezoelectric, solar cell and RF devices are connected together. Thus, the output power of this hybrid harvesting circuit is very attractive for low power electronic applications.