Communication system and audio system are important systems of aircraft. When testing the system，the voltage deviation of the input signal is carried out to meet the test requirements of special scenarios. Therefore，a signal generation circuit based on multilevel inverter is proposed by improving the class D power amplifier. The structure and operating modes of new topology are analyzed in detail，and the feasibility of DC bias，frequency and amplitude adjustment is demonstrated. According to this topology，different control modes are proposed，and the realization methods of three-level SPWM modulation and five-level SPWM modulation are explained in detail. The correctness of the control strategy and theoretical analysis is verified by PSIM simulation. Finally，the correctness of theoretical analysis and the feasibility of new topology are demonstrated by setting up an experimental platform，and the method for reducing the high-frequency oscillation at the output end of the bridge arm is given.