This paper presents a UHF CMOS MEMS resonator working at 384MHz at its bulky mechanical mode. The novel topology proposed allows us to design the resonator taking into account the coupling area of the movable resonator as an important parameter in the design. The structure is fabricated using a commercial CMOS technology. This fact allows to integrate directly the microelectromechanical structure with the electronic. This work presents the measurement of both, the stand alone resonator and the resonator with an amplification circuitry.