2024/05/24 by Izhar Izhar, Merrilyn Mercy Adzo Fiagbenu, Izhar +21 · 7 citations
Engineering · Physics and Astronomy · #Acoustic Wave Resonator Technologies #GaN-based semiconductor devices and materials #Microwave Engineering and Waveguides
paper · pdf · doi:10.48550/arxiv.2406.15431
Bulk Acoustic Wave (BAW) filters find applications in radio frequency (RF) communication systems for Wi-Fi, 3G, 4G, and 5G networks. In the beyond-5G (potential 6G) era, high frequency bands (>8 GHz) are expected to require resonators with high-quality factor (Q) and electromechanical coupling (kt2) to form filters with low insertion loss and high selectivity. However, both the Q and kt2 of resonator devices formed in traditional uniform polarization piezoelectric films of aluminum nitride (AlN) and aluminum scandium nitride (AlScN) decrease when scaled beyond 8 GHz. In this work, we utilized 4-layer AlScN periodically poled piezoelectric films (P3F) to construct high frequency (~17-18 GHz) resonators and filters. The resonator performance is studied over a range of device geometries, with the best resonator achieving a kt2 of 11.8% and a Qp of 236.6 at the parallel resonance frequency (fp) of 17.9 GHz. These resulting figures of merit are ((FoM)1=(kt2 Q)p and (FoM2=fp(FoM)1x10-9) ) 27.9 and 500 respectively. These and the kt2 are significantly higher than previously reported An/AlScN-based resonators operating at similar frequencies. Fabricated 3-element and 6-element filters formed from these resonators demonstrated low insertion losses (IL) of 1.86 dB and 3.25 dB, and -3 dB bandwidths (BW) of 680 MHz (fractional BW of 3.9%) and 590 MHz (fractional BW of 3.3%) at ~17.4 GHz center frequency. The 3-element and 6-element filters achieved excellent linearity with in-band input third-order intercept point (IIP3) values of +36 dBm and +40 dBm, respectively, which are significantly higher than previously reported acoustic filters operating at similar frequencies.