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Design of a phase-locked multimode SAW oscillator
1Microwave Acoust. Lab., McMaster Univ., Hamilton, Ont.
This study presents a surface acoustic wave (SAW) oscillator achieving enhanced stability. The new design significantly reduces phase noise for improved intermediate-term time-domain stability.
Area of Science:
- Physics
- Electrical Engineering
- Materials Science
Background:
- Surface Acoustic Wave (SAW) oscillators are crucial for stable frequency generation.
- Minimizing close-in phase noise and enhancing time-domain stability are key challenges in oscillator design.
- Multimode SAW oscillators offer flexibility but require precise control for optimal performance.
Purpose of the Study:
- To develop a multimode SAW oscillator with improved intermediate-term time-domain stability.
- To reduce close-in phase noise compared to unlocked oscillators.
- To achieve stable operation over extended periods through effective mode selection and control.
Main Methods:
- Utilized a 60-100 MHz multimode SAW oscillator.
- Incorporated a low-loss single-phase unidirectional transducer (SPUDT) comb filter.
- Implemented two varactor-based control elements and two feedback loops for mode selection and stability.
- Operated with a comb spacing of Deltaf=10 MHz.
Main Results:
- Achieved frequency deviation less than 20 Hz over two hours in each of the five comb modes.
- Demonstrated enhanced stability and reduced close-in phase noise.
- Successfully selected and stabilized specific modes of the multimode oscillator.
Conclusions:
- The developed SAW oscillator effectively enhances intermediate-term time-domain stability.
- The combination of SPUDT comb filter and feedback control is crucial for performance.
- This design offers a promising solution for applications requiring highly stable RF signals.
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