Fig. 4: Microacoustic ladder filters.

a Measured filter scattering parameter S₂₁ vs. frequency for a bank of nanoacoustic devices fabricated on the same chip and matched via ADS® (see Table 3). In b, a comparison between unmatched (raw) and matched responses. In c, the pad structure is reported, together with the probing configurations to independently measure the filter and the series and parallel resonators. In d, ADS simulated and matched 1st, 3rd, and 5th order F5 filters are shown, starting from the measured and single-mode-fitted resonator responses (see Methods). The notch depth of the 3rd and 5th order filters is exacerbated by the employment of the simple BVD model to describe the resonator response. In a real case, the dielectric losses inherent to the piezoelectric layer⁷ would cap the notch depth. Such losses were not taken into account here to be consistent with the BVD fitting used throughout this work.