Abstract:In the parallel plate capacitance model,the electrostatic force plays an irreplaceable role in the operation of CMUT.Due to the nonlinearity of the electrostatic force, the CMUT has nonlinear characteristics during the launching process. In order to eliminate and suppress the nonlinearity of CMUT, three methods are applied. Removing the DC bias voltage.Although this method can eliminate CMUT nonlinearity, it will seriously affect the performance of the emission sound pressure, sensitivity and electromechanical coupling coefficient. Changing the signal type of excitation source to suppress nonlinearity according to the effect of power spectrum suppression.The simulation results show that the suppression of CMUT nonlinearity by the cosine signal,step pulse signal and bipolar square wave is -6 dB,-10 dB and -19 dB respectively. Suppressing the nonlinearity of CMUT by adopting the linear and nonlinear compensation methods according to the double angle formula. The simulation results indicate that the suppression of CMUT nonlinearity by the linear and nonlinear compensation method is -87 dB and -78 dB respectively. From the simulation results, we come to the conclusion that the nonlinearity of the CMUT can be obviously suppressed by adopting the linear and nonlinear compensation method, which is superior to the former two methods.