The present invention exploits the combination of the amplification, provided by the integration of a FET (or any other three terminal active device), with the signal modulation, provided by the MEM resonator, to build a MEM resonator with built-in transistor (hereafter called active MEM resonator). In these devices, a mechanical displacement is converted into a current modulation and depending on the active MEM resonator geometry, number of gates and bias conditions it is possible to selectively amplify an applied signal. This invention integrates proposes to integrate transistor and micro-electro-mechanical resonator operation in a device with a single body and multiple surrounding gates for improved performance, control and functionality. Moreover, under certain conditions, an active resonator can serve as DC-AC converter and provide at the output an AC signal corresponding to its mechanical resonance frequency.