A thin-film bulk-acoustic-wave resonator-controlled oscillator on silicon

A composite ZnO bulk-acoustic-wave thin-film resonator (TFR) has been fabricated on a silicon substrate with a double-diffused BJT. Fabrication techniques unique to the integration of the TFR are discussed. The integrated TFR-BJT structure was configured as a VHF Pierce oscillator circuit with a fundamental frequency of 257 MHz. Phase noise is better than -90 dBc/Hz at a 1-kHz offset. Temperature stability is - 8.5 ppm/°C from 5°C to 65°C and - 3.75 ppm/°C from 55°C to 5°C. The integration of the TFR with active components is viewed as a development toward large-scale RF circuit integration.