1.5-GHz voltage controlled oscillator with 3% tuning bandwidth using a two-pole DSBAR filter

Area of Science:

• Electrical Engineering
• RF and Microwave Engineering
• Materials Science

Background:

• Voltage controlled oscillators (VCOs) are critical components in modern electronic systems.
• Achieving low phase noise and high power efficiency simultaneously remains a significant challenge.
• Miniature acoustic resonators offer potential for improved oscillator performance.

Purpose of the Study:

• To present the first results of a novel voltage controlled oscillator (VCO) operating in the lower gigahertz range.
• To demonstrate the performance benefits of incorporating a miniature decoupled stacked bulk acoustic resonator (DSBAR) filter within a VCO.
• To evaluate the phase noise suppression and power efficiency of the developed VCO prototypes.

Main Methods:

• Design and fabrication of a novel VCO incorporating a miniature two-pole decoupled stacked bulk acoustic resonator (DSBAR) filter.
• Characterization of the DSBAR filter's properties, including phase transition, linearity, and insertion loss.
• Testing of 1.55-GHz laboratory VCO prototypes to measure supply voltage, current, output power, efficiency, and phase noise.

Main Results:

• The novel DSBAR filter enables stable single-mode operation over a 45 MHz tuning bandwidth with negligible heat dissipation.
• Laboratory VCO prototypes achieved a 5 V supply voltage, 50 mA supply current, and 15 dBm output power.
• Demonstrated phase noise suppression of -84 dBc/Hz at 1 kHz carrier offset and < -180 dBc/Hz in the thermal noise region.
• Achieved power efficiency greater than 13%.

Conclusions:

• The integration of the DSBAR filter into a VCO design significantly improves phase noise performance and power efficiency.
• The developed VCOs show promising results for applications requiring high-performance frequency generation.
• Cascading DSBAR filters offers a pathway for further reduction of phase noise in future oscillator designs.