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 90–2450[Formula: see text]MHz. 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 2400–2483[Formula: see text]MHz. The resonant frequency shifts by 600[Formula: see text]kHz when the capacitance changes by [Formula: see text]% of the value of 21[Formula: see text]pF (or 32[Formula: see text]ppm/pF) and has an almost linear character.