Fig. 3: Resonator admittance and scatter plots.

a Measured admittance Y₁₂ vs. frequency curves for showcase resonators from this work, along with their BVD fitting. The fitting parameters are shown in Table 2. b–e Scatter plots comparing the devices from this work with resonators in the literature above 6 GHz. The optimal performance region for the synthesis of filters for the 6G mid-band is highlighted in green. The considered frequency range is 7–20 GHz, while a \(Q\cdot {k}_{t}^{2}\) product of 15 is the considered minimum requirement to achieve acceptable values of filter insertion loss. A minimum \({k}_{t}^{2}\) of 4% is also assumed to ensure a required bandwidth of 400 MHz⁴ at 20 GHz. Due to the lack of a generalized guideline for quality factor extraction, the maximum Q retrieved from the referenced publications is reported. More in detail, motional Q is used for^{25,30,32,33,37,38,51,54}, Q_3dB for^35,43, Q_max for^52,53, and Q_p for⁵⁵.