Design and Micro-Nano Fabrication of a GaAs-Based On-Chip Miniaturized Bandpass Filter with Intertwined Inductors and Circinate Capacitor Using Integrated Passive Device Technology.

Jian Chen,Shan Yang,Bao-Hua Zhu,Nam-Young Kim,Dong-Min Lee,Eun-Seong Kim,Wei Yue

doi:10.3390/nano12030347

Abstract

In this study, we propose a miniaturized bandpass filter (BPF) developed by combining an approximate circular (36-gon) winding inductor, a circinate capacitor, and five air-bridge structures fabricated on a gallium arsenide (GaAs) substrate using an integrated passive device (IPD) technology. We introduced air-bridge structures into the outer metal wire to improve the capacitance per unit volume while utilizing a miniaturized chip with dimensions 1538 μm × 800 μm (0.029 λ0 × 0.015 λ0) for the BPF. The pattern was designed and optimized by simulating different dimensional parameters, and the group delay and current density are presented. The equivalent circuit was modeled to analysis various parasitic effect. Additionally, we described the GaAs-based micro-nano scale fabrication process to elucidate the proposed IPD technology and the physical structure of the BPF. Measurements were conducted with a center frequency of 1.53 GHz (insertion loss of 0.53 dB) and a 3-dB fractional bandwidth (FBW) of 70.59%. The transmission zero was located at 4.16 GHz with restraint of 35.86 dB. Owing to the benefits from its miniaturized chip size and high performance, the proposed GaAs-based IPD BPF was verified as an excellent device for various S-band applications, such as satellite communication, keyless vehicle locks, wireless headphones, and radar.

Highlights

Passive devices such as filters, balancers, mixers, and power dividers have been widely studied in the past few years owing to the importance of radio frequency (RF)and microwaves in wireless communication systems
The remaining photoresist was peeled off using the lift-off machine for 90 s, a sufficient time to ensure the complete stripping of the PR without residue, to obtain the results shown in Subsequently, a 300 nm SiNx passivation layer was deposited on the entire surface (Step 12) to protect the device from moisture and oxidation
The two ports of the PCB are connected to the vector network analyzer (VNA) using subminiature version A (SMA) connectors

Summary

Introduction

Passive devices such as filters, balancers, mixers, and power dividers have been widely studied in the past few years owing to the importance of radio frequency (RF). While early RF research extensively studied microstrip filters considering they were low cost, easy to process, lightweight, and possessed multi-component integration capabilities, they exhibited insufficient miniaturization and higher losses. In the past few decades, several manufacturing technologies, such as monolithic microwave integrated circuits (MMICs), microelectromechanical systems (MEMSs), lowtemperature co-fired ceramics (LTCCs), and high-temperature superconductors (HTSs), Nanomaterials 2022, 12, 347. [12], where the insertion loss is 0.95 dB and the physical size is 0.0369 × 0.0428 λ0 2 They exhibit low power capability and are incapable of making design changes during manufacturing, which restricts the development of MMICs to a certain extent [13,14]. This study explores an IPD-based BPF using a GaAs substrate, which is a very important semiconductor material in the medical, communications, and military fields. We demonstrate the advantages of this research by comparing it with the published BPFs

Design and Micro-Nano Fabrication

Filter Analysis and Optimization Based on Various Parameters

Equipment Circuit Analysis

Micro-Nano Fabrication

Results and Discussion

Conclusions