Fabrication of QFN-Packaged Miniaturized GaAs-Based Bandpass Filter with Intertwined Inductors and Dendritic Capacitor.

Jian Chen,Nam-Young Kim,Bao-Hua Zhu,Zhi-Ji Wang,Eun-Seong Kim

doi:10.3390/ma13081932

Abstract

This article presents a compact quad flat no-lead (QFN)-packaged second-order bandpass filter (BPF) with intertwined inductors, a dendritic capacitor, and four air-bridge structures, which was fabricated on a gallium arsenide (GaAs) substrate by integrated passive device (IPD) technology. Air-bridge structures were introduced into an approximate octagonal outer metal track to provide a miniaturized chip size of 0.021 × 0.021 λ0 (0.8 × 0.8 mm2) for the BPF. The QFN-packaged GaAs-based bandpass filter was used to protect the device from moisture and achieve good thermal and electrical performances. An equivalent circuit was modeled to analyze the BPF. A description of the manufacturing process is presented to elucidate the physical structure of the IPD-based BPF. Measurements were performed on the proposed single band BPF using a center frequency of 2.21 GHz (return loss of 26.45 dB) and a 3-dB fractional bandwidth (FBW) of 71.94% (insertion loss of 0.38 dB). The transmission zero is located at the 6.38 GHz with a restraint of 30.55 dB. The manufactured IPD-based BPF can play an excellent role in various S-band applications, such as a repeater, satellite communication, and radar, owing to its miniaturized chip size and high performance.

Highlights

With the development of modern wireless communication systems, passive devices, such as balancers, mixers, and power splitters, play an important role in the field of radio frequency (RF)/microwave
quad flat no-lead (QFN)-packaging technology was used to protect the device from moisture and ensure good thermal and electrical performances
A dendritic capacitor was placed in the center of an approximate octagonal outer spiral inductor, and both are composed of three laminated conductor layers

Summary

Introduction

With the development of modern wireless communication systems, passive devices, such as balancers, mixers, and power splitters, play an important role in the field of radio frequency (RF)/microwave. Bandpass filters (BPFs) have been vastly studied in the field of microwave filters, as they form an important block of RF/microwave integrated circuits and systems. Researchers have been exploring processing techniques that lead to high precision, mass production, and low cost. Recent studies have demonstrated many advanced manufacturing technologies, including low-temperature co-fired ceramics (LTCC), monolithic microwave integrated circuits (MMICs), high-temperature superconductor (HTS), micro-electromechanical systems (MEMS), and micro-fabrication techniques, which promote the development and implementation of BPF design. The disadvantage of LTCC is that the size of the ceramic and the processing plate shrink after

Methods

Results

Conclusion