Scaling LLSAW filters on engineered LiNbO3-on-SiC wafer for 5G and Wi-Fi 6 wideband applications

With the surge in fifth-generation (5G) wireless systems and escalating growth of data traffic, the push for higher carrier frequencies with wider bandwidths intensifies. This work reveals the outstanding capabilities of wafer-level longitudinal leaky surface acoustic wave (LLSAW) devices on the lithium niobate on insulator (LNOI) platform in scaling SAW technology beyond 4 GHz by mass-produced lithography. Leveraging SiC-based LNOI, the fabricated LLSAW resonators showcase remarkable quality factor (Q), scalable electromechanical factor <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mfenced> <mml:mrow> <mml:msubsup><mml:mrow><mml:mi>k</mml:mi></mml:mrow> <mml:mrow><mml:mtext>eff</mml:mtext></mml:mrow> <mml:mrow><mml:mn>2</mml:mn></mml:mrow> </mml:msubsup> </mml:mrow> </mml:mfenced> </mml:mrow> </mml:math> from 14% to 28%, and record high figure-of-merit (FoM) of 166 to 222 at 5-6 GHz. Targeted for diverse bands, LLSAW filters with adaptable bandwidths have been realized on specific LN-on-SiC platforms. The filters covering the n79 full band with a minimum insertion loss (IL_min) of 0.85 dB and the 5 GHz Wi-Fi full band with an IL_min of 1.62 dB, have been demonstrated for the first time. These findings position LLSAW on LN-on-SiC platform as a promising commercial-grade candidate for pushing the SAW paradigm towards high frequency and wideband filtering.