Tunable high-Q SAW resonator loaded on a changing capacitance

Abstract

A tunable high-Q surface acoustic wave (SAW) resonator in the form of several parallel-connected interdigital transducers loaded on a varying capacitance on lithium niobate substrates was developed and studied. The working frequency range was 90–2450MHz. A method of calculating such resonators, considering losses in the metal film as well as losses due to the propagation of SAWs and transformations into bulk waves is proposed. Such a design allows one to obtain a quality factor over 5000 in the frequency range 2400–2483MHz. The resonant frequency shifts by 600kHz when the capacitance changes by ±25% of the value of 21pF (or 32ppm/pF) and has an almost linear character.

Keywords

• crystal growth
• directional crystallization
• defects
• internal stresses
• analytical methods