5.9 GHz Longitudinal Leaky SAW Filter With FBW of 9.2% and IL of 1.8 dB Using LN/Quartz Structure
Rongxuan Su, Sulei Fu, Huiping Xu, Zengtian Lu, Peisen Liu, Boyuan Xiao, Rui Wang, Fei Zeng, Cheng Song, Weibiao Wang, Feng Pan
Abstract
Improving frequency and bandwidth is the essential path for the surface acoustic wave (SAW) filter to keep its leadership in the 5G or sub-6G system. In this work, we present high frequency longitudinal leaky SAW (LLSAW) devices based on 128° <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${Y}$ </tex-math></inline-formula> -90° <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${X}$ </tex-math></inline-formula> LiNbO3/160° <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${Y}$ </tex-math></inline-formula> -90° <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${X}$ </tex-math></inline-formula> Quartz structure, whose parameters were optimized through simulation. Moreover, unlike other substrates suffering from obvious ripples, device using Quartz substrate exhibits near spurious free response in a wide frequency range. The fabricated resonator features phase velocity of 6194 m/s, effective electromechanical coupling factor of 12.0%. Subsequently, 5.924 GHz LLSAW filter with fractional bandwidth (FBW) of 9.2% and insertion loss (IL) of 1.82 dB was realized.