they are excited by mixed-frequency signals. This interest has been stimulated by their potential use in such fields as communications (Wong and Nguyen 2004), logic functions (Mahboob et al. 2011(Mahboob et al. , 2013, and atomic microscopy (Garcia and Herruzo 2012). For instance, Mahboob et al. (2011) explored that use in logic gates. In order to display new logic architectures, they employed mechanical oscillators at different frequencies. Using a single resonator, they built a new algorithm to eradicate wiring by means of condensed Boolean logic. They simultaneously executed their logic gates in efforts to provide a parallel logic circuit in a single mechanical resonator. Mahboob et al. (2013) demonstrated parametric coupling between multiple vibrations modes in an electromechanical resonator via a strain inducing piezoelectric pump. This parametric coupling can be useful because it rapidly quenches the vibration of the modes, a reduction that leads to the exchange of the vibration of the modes and of energy. Moreover, their technique helps control the oscillation amplitude and generates high speed. The effect of mixed frequency excitation can be a viable solution in these areas due to mixing frequencies through quadratic electrostatic forces. This method has been found in (Wong and Nguyen 2004; Garcia and Herruzo 2012) to realize down converters, mixers, and filters.Many researchers investigated different ways of mixing signals. Hetch (1977) analyzed the acousto-optic diffraction with multiple waves at different carrier frequencies using a coupled mode formulation. Later, a three-wave mixing technique was used to find nonlinear index for different transparent material (Garcia and Herruzo 2012). Nayfeh and Mook (1979) derived the analytical expression of multi frequency excitation of a system with a quadratic nonlinearity using straightforward expansion and the method of the multiple scales. Elnagarand and EI-Bassiouny (1992) used the method of multiple scales to find the response Abstract We investigate experimentally and theoretically the dynamics of a capacitive resonator under mixed frequency excitation of two AC harmonic signals. The resonator is composed of a proof mass suspended by two cantilever beams. Experimental measurements are conducted using a laser Doppler vibrometer to reveal the interesting dynamics of the system when subjected to two-source excitation. A nonlinear single-degree-of-freedom model is used for the theoretical investigation. The results reveal combination resonances of additive and subtractive type, which are shown to be promising to increase the bandwidth of the resonator near primary resonance frequency. Our results also demonstrate the ability to shift the combination resonances to much lower or much higher frequency ranges. We also demonstrate the dynamic pull-in instability under mixed frequency excitation.