Low Velocity HAL SAW Resonator Using LiNbO3 Thin Plate on Quartz Substrate

This paper reports a low velocity hetero acoustic layer (HAL) surface acoustic wave (SAW) resonator using a combination of 11°YX lithium niobate (LN) thin plate and YX quartz (Qz) substrate with copper (Cu) interdigital transducers (IDTs). The fabricated one-port (1-port) SAW resonator attained a low effective velocity of 2416 ms
^-1
at resonance with an impedance ratio (Z-ratio) of 80 dB and a relative bandwidth (BW) of 11%. The resonator has temperature coefficient of frequency (TCF) of -129 ppm°C
^-1
at resonance frequency (f
r
) and -117 ppm°C
^-1
at antiresonance frequency (f
a
). The resonator has a roughly 30% lower velocity compared with the previously developed LT/ Qz HAL SAW resonator and a roughly 40% slower than the metallized SH-SAW velocity on 11°YX LN, indicating its potential for low-band filter applications.