In this paper, we propose a solution for the narrow band operation which is one of the main issues in the operation of vibration-based energy harvesters, i.e. micro power generators (MPGpsilas). The solution is based on utilizing piecewise-linear oscillators along with decreasing the effective damping ratio of the resonator. The system is modeled and a macro electromagnetic vibration-based energy harvester was examined to verify analytical results. The feasibility of applying such technique on a MEMS-based electromagnetic MPG is discussed.