On-Chip Miniaturized Bandpass Filter Using GaAs-Based Integrated Passive Device Technology For L-Band Application

Area of Science:

• Electrical Engineering
• Materials Science
• Microwave Engineering

Background:

• Miniaturized bandpass filters (BPFs) are crucial components in modern radio-frequency (RF) systems.
• Existing BPF designs often face challenges with size, performance, and fabrication complexity.
• Integrated Passive Device (IPD) technology offers a promising platform for developing compact and high-performance RF components.

Purpose of the Study:

• To design and fabricate a miniaturized bandpass filter (BPF) utilizing integrated passive device (IPD) technology on a Gallium Arsenide (GaAs) wafer.
• To enhance mutual inductive effects and achieve a compact differential geometry for the BPF.
• To analyze and model the frequency-dependent lumped elements for accurate equivalent circuit representation.

Main Methods:

• Design and fabrication of a BPF using two spiral intertwined inductors, a central capacitor, and interdigital structures on a GaAs wafer.
• Incorporation of five air-bridge structures to improve mutual inductance and differential geometry.
• Modeling using the segment method, mutual inductance approach, and simulated scattering parameters (S-parameters).
• Fabrication via a 16-step GaAs-based IPD process flow.

Main Results:

• The fabricated BPF operates at a 2 GHz center frequency.
• Achieved insertion losses of 0.38 dB and return losses of 40 dB.
• Demonstrated an ultrawide 3-dB fractional bandwidth of 72.53%.
• A transmission zero was observed at 5.32 GHz.
• Simulations showed good controllability of resonant frequency with variations in inductor turns and metal thickness.

Conclusions:

• The developed miniaturized BPF exhibits excellent RF performance, including low losses and ultrawide bandwidth.
• The IPD technology on GaAs wafer is suitable for fabricating compact and high-performance BPFs.
• The design approach offers good controllability and potential for further optimization in RF applications.