Geometry optimization of broadband, planar, spiral inductors via continuous trace width modulation

Area of Science:

• Electrical Engineering
• Electromagnetics
• Materials Science

Background:

• Planar inductors are crucial components in electronic circuits.
• Constant-width inductors show frequency-specific performance advantages.
• Broadband inductor design remains a challenge for DC to low RF applications.

Purpose of the Study:

• To investigate the broadband performance of variable-width planar inductors.
• To compare variable-width designs against constant-width inductors from DC to several hundred MHz.
• To demonstrate the efficacy of continuous trace width modulation for enhanced inductor performance.

Main Methods:

• Designed and simulated circular spiral inductors with constant and variable trace widths.
• Fabricated selected inductor designs.
• Experimentally characterized DC magnetic flux density and RF performance (inductance, quality factor) using reflection coefficient measurements.

Main Results:

• Variable-width inductors generated stronger DC magnetic fields under equivalent bias.
• Variable-width inductors exhibited higher quality factors in the low RF range.
• Consistent performance enhancement across the entire DC to low RF spectrum was observed.

Conclusions:

• Continuous trace width modulation is an effective technique for designing high-performance broadband inductors.
• Variable-width inductors offer superior performance compared to constant-width designs across a wide frequency range.
• This approach enables inductor optimization for broad spectral applications, not just specific frequencies.