Single-chip multiple-frequency rf microresonators based on aluminum nitride contour-mode and FBAR technologies

This work reports experimental results on a new class of multiple-frequency contour-mode bulk acoustic wave aluminum nitride resonators that were co-fabricated on the same silicon chip with suspended dim film bulk acoustic resonators (FBAR). The novel contour-mode technology combined with FBAR resonators permit the fabrication of integrated single-chip RF platforms that can cover IF and RF frequencies of particular interest to the handset market. High Q ranging from 2,000 to 4,000 were demonstrated for rectangular and ring shaped contour-mode resonators in air at frequencies as high as 473 MHz. FBAR resonators with Q of 2,000 at 1.75 GHz were fabricated on the same substrate. To further prove the contour-mode technology, ladder filters at 93 and 236 MHz were demonstrated with insertion losses of 4 and 8 dB, respectively, 3 dB bandwidth of 0.3% and high out-of-band rejection (larger than 26 dB). In addition a low phase noise (less than - 110 dBc/Hz at 10 kHz offset) oscillator was realized using a 224 MHz ring resonator in a standard pierce design.