Novel VCO Architecture Using Series Above-IC FBAR and Parallel LC Resonance

• Published in: IEEE journal of solid-state circuits Vol. 41; no. 10; pp. 2248 - 2256
• Main Authors: Ostman, K.B., Sipila, S.T., Uzunov, I.S., Tchamov, N.T.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.10.2006; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Acoustic wave devices, piezoelectric and piezoresistive devices; Applied sciences; BiCMOS integrated circuits; Circuit properties; Design. Technologies. Operation analysis. Testing; Electric, optical and optoelectronic circuits; Electronic circuits; Electronics; Exact sciences and technology; Film bulk acoustic resonator (FBAR) voltage-controlled oscillator (VCO); Film bulk acoustic resonators; Frequency; Germanium silicon alloys; Global Positioning System; Integrated circuits; Narrowband; Noise; Oscillators; Oscillators, resonators, synthetizers; Phase noise; piezoelectric resonator oscillators; Resonance; Resonators; Satellite navigation systems; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Silicon germanides; Silicon germanium; Transistors; Tuning; tuning range; Voltage-controlled oscillators; Phase noise; Performance evaluation; Semiconductor alloys; Acoustic wave resonator; Film bulk acoustic resonator (FBAR) voltage-controlled oscillator (VCO); High Q factor; integrated circuits; Voltage controlled oscillator; tuning range; Bulk acoustic wave devices; Transistor; piezoelectric resonator oscillators; Narrow band; Voltage control; Tuning; BiCMOS technology; Integrated circuit; Piezoelectric resonator; Monolithic integrated circuit; Piezoelectric thin films
• ISSN: 0018-9200; 1558-173X
• DOI: 10.1109/JSSC.2006.881567

A quasi-monolithic voltage-tunable film bulk acoustic resonator (FBAR) enhanced oscillator for 2.1 GHz in 0.25-mum SiGe BiCMOS technology is designed, fabricated, and evaluated. The narrow-band FBAR was built above the SiGe circuit through later Si post-processing steps. The oscillator is based on a two-transistor loop structure and uses two resonators, namely a parallel LC tank and an above-IC FBAR in its series-resonant mode. The improvement in phase noise performance is significant compared to a similar reference LC voltage-controlled oscillator (VCO), with the best phase noise being -144.1 dBc/Hz at an offset of 1 MHz and -149.6 dBc/Hz at 3 MHz. The architecture offers advantages in overcoming frequency tuning difficulties usually present when using high-Q resonators. Although the width of the tuning range comes at some cost on phase noise, the measured performance satisfies contemporary wireless standards such as GPS