6H-5 Design, Elaboration and Characterization of Coupled Resonator Filters for WCDMA Applications

This work presents the design, manufacturing and characterization of bulk acoustic wave coupled resonator filter (BAW CRF) for W-CDMA applications. Aluminum nitride resonators with molybdenum electrodes are acoustically coupled through a W/SiO
₂
multi-layered stack and insulated by a fully dielectric SiN/SiOC Bragg mirror. This configuration provides galvanic isolation between input and output making CRF suitable for single-to-balanced conversion. Measurements of both single-ended and single-to-balanced filters display bandwidth and out-of-band attenuation close to W-CDMA specifications. Minimum insertion loss of 2.9 dB is measured whereas strong spurious resonances are observed. Experimental results on spurious modes suppression using specific border region are discussed