In this study, a method for mechanical frequency up-conversion using a pendulum is proposed, which can increase the power transfer and reduce the vibration amplitude compared to the simple pendulum under wide-band excitation frequencies lower than the resonance frequency of the structure. The proposed structure consists of a pendulum that is located near a shock absorber with a high restitution coefficient. The presence of shock absorber reduces the displacement of the mass, while the frequency up-conversion effect allows the use of a structure with a resonant frequency higher than the excitation frequency. Both of these effects lead to a smaller device size. This structure can also be used in a low frequency energy harvester. For this purpose, the principles of operation are discussed and a mathematical model of the structure is expressed. The mathematical model is used for simulation in order to analyze the dynamics of the structure. Simulations are performed using a wide bandwidth excitation in order to more closely model real-world vibration conditions. It is shown that the frequency up-conversion mechanism has the ability to increase the performance compared to a simple pendulum structure.