Design and Characterisation of High-Q Solidly-Mounted Bulk Acoustic Wave Filters

Bulk acoustic wave resonator with suppressed energy loss using improved lateral structure

“…As BAW resonator shows low vertical acoustic leakage due to air-gap structure or alternating acoustic mirror stacks implemented underneath the resonator, it performs lower losses and higher Q-factors than surface acoustic wave (SAW) resonators. Although BAW resonators utilize longitudinal acoustic waves, lateral acoustic waves are also generated in a large amount especially during anti-resonance [4,5,6,7]. Suppression of this lateral acoustic wave leakage is important for its antiresonance performances such as Q a and kt 2 .…”

A design procedure for an acoustic mirror providing dual reflection of longitudinal and shear waves in Solidly Mounted BAW Resonators (SMRs)

“…This demands BAW resonators which constitute the narrow band filters to be nearly loss-free. Hence one of the important goals of the BAW community is to come up with high Q resonators for RF filters by minimizing the losses [4][5][6][7][8].…”

Reflector stack optimization for bulk acoustic wave resonators

“…mechanical waves), rather than electromagnetic (EM) waves, are that device size can be orders of magnitude smaller due to a much lower mechanical wavelength compared to the EM wavelength at a given frequency. However, in both the domains of optics and acoustics, 7 the field equations have the same mathematical form which implies any technique used in EM field theory can be applied to acoustics with appropriate transformation analogies [36]. The work of this thesis ascertains that the principles of one physical domain (optics) can be inherited for the application in another physical domain (acoustics), the wave concepts being the same in all the domains.…”

“…In the case of SMRs, loading the reflector stack with a high acoustic impedance metal also seems to improve the coupling coefficient [35], [36].…”

“…This parasitic coupling can be eliminated by patterning of the Bragg reflector as proposed in [6], [34]. An alternative approach is fabricating the SMR on a dielectric reflector [10], [35] and [36].…”