Employing a macrospin simulation and the Technology-Computer-Aided-Design device simulator, we calculated the output voltage of serially connected spin torque nano-oscillators (STNOs) integrated directly on a metal-oxide-semiconductor field-effect-transistor (MOSFET). Synchronization of the STNOs is induced by both electrical and magneto-dipolar couplings between the STNOs. In this model, the voltage across the load resistance connected to the STNOs in series acts as the gate voltage of the MOSFET. We revealed that the voltage gain of the STNOs directly integrated on the MOSFET is determined by combining the gain of the synchronized STNOs and MOSFET amplifier, and consequently, the output power of the STNOs is significantly enhanced. In addition, the output voltage of the synchronized STNOs depended on the load resistance.