On‐chip miniaturized bandpass filter using gallium arsenide‐based integrated passive device technology

Abstract

The paper proposes a miniaturized bandpass filter (BPF) using gallium arsenide (GaAs)‐based integrated passive device (IPD) technology. The proposed filter is evolved from traditional third order BPF, and it achieves a wide operation frequency band covering three 5G sub‐bands including 3.4–3.5 GHz, 3.5–3.6 GHz, and 4.8–4.9 GHz. The performance of out‐of‐band rejection is improved by introducing three transmission zeros (TZs). As known, adding cross coupling and LC resonator are the general methods to improve out‐of‐band rejection. Therefore, the first TZ at 5.85 GHz is obtained at the upper sideband by adding a capacitive coupling between the source port and resonator 2, which is a cross‐coupling mode. According to the coupling matrix, the value of the added capacitance can be calculated and optimized. Another TZ at 2.36 GHz is occurred at the left side of passband as a serial LC resonator is connected in parallel with filter near the input port. The third TZ at 7.74 GHz is generated at the upper sideband due to a serial LC resonator connected in parallel with the load terminal of the filter. The values of components in LC resonators can be calculated, too. Finally, the whole filter is optimized in full‐wave electromagnetic simulation software HFSS. The proposed filter is fabricated and measured, and the results show that it has a wide −10 dB frequency band from 3.3 GHz to 4.9 GHz and a maximum insertion loss of 2.5 dB. In addition, it has a good frequency selectivity with a rectangular coefficient of 1.67 and out‐of‐band suppression higher than 20 dB in a wide stopband. The filter adopts compact placement and has a relative miniaturized electrical size of 0.298 λ02, which is about 55% smaller than recently reported one.

Miniaturized IPD bandpass filter design with high out‐of‐band rejection for 5G applications

“…In addition, adding cross coupling is also a general method to improve out-of-band rejection. 10 In this letter, a design of miniaturized siliconbased IPD BPF with high out-of-band rejection is proposed. In this design, two pairs of TZs are introduced at high and low frequencies based on the cascade of the improved high-pass filter and low-pass filter.…”

“…In reference, 9 TZs were introduced by using lumped‐element bisected‐pi sections at the filter input/output. In addition, adding cross coupling is also a general method to improve out‐of‐band rejection 10 …”

Miniaturized IPD bandpass filter with controllable transmission zero based on modified lumped T‐section

“…1 Consequently, there has been extensive research on developing high-performance and miniaturized filters in recent years. [1][2][3][4][5][6][7][8][9][10] A novel synthesis method for lumped-element bandpass filters is proposed in Chen et al, 1 and A design methodology for optimized minimum inductor bandpass filter (BPF) is presented in Taslimi and Mouthaan. 2 In addition, a glass-integrated passive device bandpass filter using synthesized stepped impedance resonators is presented in Tseng et al 3 However, all their proposed designs are mainly designed to verify their filter synthesis methods, so the filters performance such as the size and insertion loss cannot be effectively controlled.…”

“…To improve the out-of-band rejection of the filter, adding transmission zero (TZs) to the filter is an effective method. [5][6][7] In Xu et al, 5 the paper utilizes the coupling matrices to design a compact lowtemperature cofired ceramic (LTCC) bandpass filter which introduces TZs at both sides of the filter passband to enhance the selectivity. In Zhao et al, 6 TZs are generated by stepped-impedance stubs to obtain high selectivity.…”

A compact 5G band N77 bandpass filter with multiple zeros based on GaAs integrated passive device process

“…The out-of-band suppression of lumped bandpass filters (BPFs) can also be improved by generating transmission zeros through interstage and cross-coupling. [10][11][12][13][14][15][16][17] To decrease the size of the chip, an integrated passive device (IPD) technology [18][19][20][21] was developed to fabricate on-chip filters. Band N77 is an important band for 5G-NR applications, and to improve the sensitivity and also avoid interference to other frequency bands such as Bluetooth, GPS, and WiFi band.…”