This paper presents the design of an ultra-low power energy scavenging system capable of collecting and managing energy from ambient vibrations and RF electromagnetic waves. Firstly, low power and broadband equiangular spiral antenna which is able to receive and rectify ambient RF radiation is designed and simulated. The energy transducers, commercial piezoelectric generators with a wide frequency range of 26 - 205Hz and the designed spiral antenna are evaluated and characterized to maximize the efficiency. Secondly, the power electronic circuits involved in the energy harvesting are designed in 0.6um CMOS technology and the simulation results are presented. Charge pumps, rectifier and Low drop-out regulator (LDO) were optimized to operate with low voltage ranges since the energy produced by the piezoelectric generator and the equiangular spiral antenna is found to be in microwatts and less from the test results. The AC output from the piezoelectric generator is rectified and boosted to required output level using an AC-DC charge pump. Rectifier and DC-DC charge pump are adopted for the efficient conversion of voltage from the broadband antenna. A back-up battery is provided for the start-up of DC-DC charge pump at low input conditions. An LDO with a drop-out voltage of less than 400mV is designed to provide regulated output of 4.1V to the battery. Finally, the collected energy is stored in a 50uAh capacity thin film battery which is intended for low-voltage and low-power applications.