A High-Frequency-Compatible Miniaturized Bandpass Filter with Air-Bridge Structures Using GaAs-Based Integrated Passive Device Technology

Abstract

This paper reports on the use of gallium arsenide-based integrated passive device technology for the implementation of a miniaturized bandpass filter that incorporates an intertwined circle-shaped spiral inductor and an integrated center-located capacitor. Air-bridge structures were introduced to the outer inductor and inner capacitor for the purpose of space-saving, thereby yielding a filter with an overall chip area of 1178 μm × 970 μm. Thus, not only is the chip area minimized, but the magnitude of return loss is also improved as a result of selective variation of bridge capacitance. The proposed device possesses a single passband with a central frequency of 1.71 GHz (return loss: 32.1 dB), and a wide fractional bandwidth (FBW) of 66.63% (insertion loss: 0.50 dB). One transmission zero with an amplitude of 43.42 dB was obtained on the right side of the passband at 4.48 GHz. Owing to its miniaturized chip size, wide FBW, good out-band suppression, and ability to yield high-quality signals, the fabricated bandpass filter can be implemented in various L-band applications such as mobile services, satellite navigation, telecommunications, and aircraft surveillance.

A Highly Selective and Compact Bandpass Filter with a Circular Spiral Inductor and an Embedded Capacitor Structure Using an Integrated Passive Device Technology on a GaAs Substrate

“…A transmission zero is designed to locate at 3.7 GHz, where the admittance parameter Y 21 equals zero, with a magnitude of S 21 to be 36 dB in the rejection band. The location of transmission zero can be slightly changed with the dimension; however, it should be noted that it may affect the variations of other parameters, such as bandwidth and selectivity [18,21]. A sharp roll-off is obtained both in the lower and upper bands, from 20 dB to 3 dB attenuation points, which confirms the good skirt performance.…”

“…Table 1 compares on-chip filters based on different processes with the proposed BPF, which provides higher performance with fewer metal layers than a low temperature co-fired ceramic BPF [8] or a glass IPD BPF [22]. The return loss above 20 dB of the proposed BPF indicates that almost no reflected signal occurs at the center frequency, and the best insertion loss was obtained among the compared BPFs [8,[21][22][23][24][25]. GaAs can provide better insulation and less signal loss than silicon substrate; in addition, the working power of GaAs is higher than glass [26].…”

“…The seed metal is selectively added to increase adhesion. A thin SiN x layer is deposited on the 200 µm thick GaAs substrate, to form a flat surface, and top metal for long-term protection, with a thickness of 100 nm [19][20][21]. The dielectric constant (ε r ) of GaAs is 12.85, with a loss tangent of 0.006.…”

Monolithic Heterogeneous Integration of 3D Radio Frequency L−C Elements by Self‐Rolled‐Up Membrane Nanotechnology

“…[13][14][15][16] The swift development of the Internet of Things (IoT) [17][18][19][20] further pushes the advancement of wearable and implantable technologies that are reliant on microsupercapacitors [20][21][22][23][24][25][26][27] and passive L−C network to enable wireless and battery-free sensing. [28] Novel L−C filters or resonators structures that have footprints of a few square millimeters have also been constructed using interdigital MEMS, [29] substrate-integrated waveguides, [30] air-bridge structures, [31] and out-of-plane actuation. [32] Reconfigurability, stretchability, and bendability are of great concern to the miniaturization of passive L−C components, [12,33,34] as they enable more efficient use of chip area and versatility for device integration toward a wider set of applications.…”

Tunable active inductor based VCO and BPF in a single integrated design for wireless applications in 90 nm CMOS process

“…So, the BPF as a significant block rejects unwanted frequencies. Furthermore, BPFs, along with superior performance and optimized area, enhances the overall performance of the RF system 7 . LC BPFs and RC BPFs are the two most widely used filters' topologies.…”