Revealing Hidden Resonances Through an Innovative Bonding Wire Strategy

This study presents a novel feedthrough suppression technique for MEMS resonators, leveraging additional parallel bonding wires to mitigate parasitic signal interference. Unlike the previous approach [1] that relies on specific layout designs to induce electromagnetic cancellation effect, the proposed method focuses on the packaging level of the resonant device rather than modifications of its mechanical structure. By introducing extra bonding wires on each I/O pad, the technique in this work provides a universal and cost-effective solution compatible with standard device structures. Experimental validation is conducted on a Thin-Film Piezoelectric-on-Silicon (TPoS) resonator operating in a conventional length-extensional mode. Results demonstrate consistent feedthrough suppression of approximately 20 dB across a broad frequency range, significantly enhancing the visibility of higher-order mode (HOM) resonances. The stopband rejection (SBR) of HOM improves from less than 3 dB to nearly 7 dB, enabling clearer resonance detection. This proposed approach offers a straightforward and practical means to enhance signal clarity and oscillator performance in MEMS devices. Effectively suppressing feedthrough facilitates the identification of originally buried resonance modes, benefiting applications in frequency control and precision sensing.