2 BAW Technology Overview

TI’s BAW resonator technology utilizes piezoelectric transduction to generate high-Q resonance at 2.5 GHz. The resonator is defined by the quadrilateral area overlaid by top and bottom electrodes. Alternating high- and low-acoustic impedance layers form acoustic mirrors beneath the resonant body to prevent acoustic energy leakage into the substrate. Furthermore, these acoustic mirrors are also placed on top of the resonator stack to protect the device from contamination and minimize energy leakage into the package materials. This unique dual-Bragg acoustic resonator (DBAR) allows efficient excitation without the need of costly vacuum cavities around the resonator. As a result, TI’s BAW resonator is immune to frequency drift caused by adsorption of surface contaminants and can be directly placed in a non-hermetic plastic package with the oscillator circuitry in standard oscillator footprints (3.2 mm × 2.5 mm and 2.5 mm × 2.0 mm).