A Tunable Two-Stage Bandpass Filter Incorporating Two Electromagnetically Coupled Curved Beams

The snap through phenomenon of curved beam structures offers the possibility for designing high-performance filters, however, superharmonic resonances outside the filter’s passband are difficult to be attenuated. Therefore, a two-stage bandpass filter incorporating two electromagnetically coupled curved microbeams is designed, which possesses excellent specifications of sharp switching in the stopband and flat bandwidth compared to single curved-beam based filter. The reduced-order model considering the nonlinear electromagnetic forces and geometric nonlinearities is established, and discretized using the Galerkin method. Then, the resulting static and dynamic reduced order models are numerically solved. Extensive numerical simulation results show that the improved filter has a rectangular coefficient close to 1.0, a passband ripple of 0.2 dB, and a bandwidth ratio of 14.8%, which drastically reduces the stopband interference to 10% of the passband signal. Finally, the effects of DC voltage, AC voltage and coupling strength on the center frequency and bandwidth are parametrically investigated, where the center frequency can be tuned between 23.81 kHz and 25.16 kHz and the bandwidth covers the frequency range from 22.46 kHz to 26.05 kHz. [2024-0054]