Microwave oscillators incorporating high performance distributed Bragg reflector microwave resonators.

Area of Science:

• Applied Physics
• Microwave Engineering
• Materials Science

Background:

• Existing resonator technologies have limitations in achievable quality factors (Q-factors).
• High-Q resonators are crucial for advanced electronic applications, including stable oscillators.

Purpose of the Study:

• To introduce and characterize a novel resonator structure with significantly enhanced Q-factors.
• To investigate the impact of structural symmetry on resonator performance.
• To demonstrate the practical application of these resonators in oscillator circuits.

Main Methods:

• Design and theoretical analysis of a microwave cavity resonator utilizing 3D distributed Bragg reflectors (DBRs) constructed from low-loss sapphire.
• Development of a precise alignment tool to ensure the required fabrication tolerances and maintain structural symmetry.
• Fabrication and experimental testing of two prototype resonators operating at 9.0 GHz.

Main Results:

• The novel resonator structure demonstrated unloaded Q-factors exceeding 700,000 at room temperature.
• Theoretical analysis confirmed that resonator performance is highly sensitive to the alignment of DBR components and the preservation of symmetry.
• The fabricated resonators were successfully integrated into two-port feedback oscillator circuits, with phase noise measurements performed.

Conclusions:

• The developed 3D DBR sapphire resonator structure offers a pathway to achieving unprecedented Q-factors.
• Precise alignment is critical for optimal performance, preventing the degradation of high-Q modes by low-Q hybrid modes.
• These high-Q resonators show promise for improving the performance of microwave oscillators.