Intermodulation in capacitively coupled microelectromechanical filters

A compact model for third-order intermodulation in capacitively coupled microelectromechanical filters is derived. A simple expression for the input third-order intercept point is given. This is valuable in designing micromechanical filters, for example, for communication applications. The validity of the analytic model is verified with numerical harmonic-balance simulations and experimental measurements

Third-order intermodulation in microelectromechanical filters coupled with capacitive transducers

Abstract—Third-order intermodulation in capacitively cou-pled microelectromechanical filters is analyzed. Parallel-plate transducers are assumed and, in addition to the capacitive non-linearities, also the usually much weaker second- and third-order mechanical resonator nonlinearities are taken into account. Closed-form expressions for the output signal-to-interference ratio (SIR) and input intercept point are derived. The analytical results are verified in experiments and in numerical harmonic-bal-ance simulations. It is shown that intermodulation as a function of frequency is asymmetric with respect to the passband. The results are valuable in designing micromechanical filters, for example, for communication applications. [1544] Index Terms—Communication systems, intermodulation distor-tion, microelectromechanical devices. I