Piezoelectric Lamb-wave resonators at ultra-high frequencies
Next generation wireless communication systems demand high-density (high level of integration) and low-power-consuming bandpass filters. Passive MEMS-based filters (RF-MEMS) with high quality factor (Q-factor) fulfil these demands and are therefore one of the promising means to further miniaturization of bandpass filters. Among RF-MEMS filters, Lamb-wave filters are the most promising candidates as they are released from the substrate and do not have energy-loss to the substrate, providing high Q-factor performance. Additionally, the resonance frequency of Lamb-wave filters are mainly depend on lateral (in-plane) dimensions, rather than the thickness of the deposited thin-films, which enables a single fabrication process for different resonance frequencies. In this talk, I will present Lamb-wave filters using PZT-based transduction, going into detail on how to overcome parasitic signals, which is of crucial importance at ultra-high frequencies. Furthermore, I will present a new concept for bandpass filters, which allows the use of PZT thin-film at ultra-high frequencies.