RF Channel-Select Micromechanical Disk Filters-Part I: Design.

Area of Science:

• Electrical Engineering
• Mechanical Engineering
• Materials Science

Background:

• Radio frequency (RF) front-ends require filters to select desired channels and reject interference.
• Existing filters often struggle with strong adjacent channel blockers, necessitating higher dynamic range in subsequent stages.
• Micromechanical filters offer a potential solution due to their high quality factors (Q).

Purpose of the Study:

• To introduce a hierarchical design flow for micromechanical RF channel-select filters.
• To enable filters with tiny fractional bandwidths for effective adjacent channel rejection.
• To reduce the dynamic range requirements of RF front-end components.

Main Methods:

• A hierarchical design approach inspired by VLSI circuit design.
• Utilizing vibrating micromechanical disk building blocks with Q > 10,000.
• Employing array composites of coupled disks and beams for impedance matching and differential operation.
• Designing filters with specific coupling mechanisms (half-wavelength, full-wavelength, quarter-wavelength beams).

Main Results:

• The design hierarchy enables low passband loss for tiny fractional bandwidths.
• Second-level hierarchy using array composites reduces filter termination impedance.
• Third-level hierarchy with full-wavelength beams achieves fully balanced differential operation.
• Final stage with quarter-wavelength beams generates the desired passband.

Conclusions:

• The proposed hierarchical design flow is effective for creating high-performance micromechanical RF channel-select filters.
• This approach facilitates the design of filters capable of handling strong adjacent channel blockers.
• The methodology lays the groundwork for advanced RF front-end architectures with reduced dynamic range requirements.