title: Impact of SAW device passivation on RF performance.
abstract: Passivation layers consisting of sputtered A12O3 have been deposited onto SAW devices for the purpose of reducing the incidence of shorts. A coupling-of-modes model was used with one-port resonators, coupled resonator filters (CRF), and test structures. The passivation layer stiffens the surface with a velocity increase proportional to tau/lambda, where tau is the passivation layer thickness. Attenuation is increased slightly, producing a 0.25-dB increase in the loss of a one-port resonator at 314 MHz. The effect on reflectivity is minimal and of much lesser importance to the designer.
authors.affiliation: RF Monolithics, Inc, Dallas, TX 75244, USA. marks@rfm.com
authors.forename: B W
authors.initials: BW
authors.lastname: Marks
authors.forename: D W
authors.initials: DW
authors.lastname: Sheddrick
authors.forename: S
authors.initials: S
authors.lastname: Jen