This paper presents a MEMS-based electromagnetic (EM) energy harvester for low frequency and low acceleration vibrations. The harvester is an improved version of , which operates with the frequency up conversion (FupC) principle. The former structure was composed of a low-frequency diaphragm carrying a magnet and 16 high-frequency cantilevers with coils. In this work, the phase difference between the coil outputs, leading to voltage cancellation in serial connection, has been eliminated by using a single coil placed on a diaphragm. Furthermore, the placement and the volume of the magnetic film have been modified for better magnetic coupling. The RMS values of the generated voltage and delivered power to an equivalent resistive load have been measured as 6.94 mV and 1.2 nW, respectively with 10 Hz, 3 mm peak to peak vibrations (0.6 g acceleration). About 32-fold increase in the peak power output has been demonstrated with the presented energy harvester with respect to the previous work.