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In this study, a novel bandpass filter (BPF) characterized by low insertion loss (IL) and the presence of two transmission zeros (TZs) based on integrated passive device (IPD) technology is introduced. The design incorporates a low‐pass filter and a high‐pass filter which both exhibit strong out‐of‐band suppression performance. The control structure for TZs is constructed by cascading the inductance and capacitance components. The TZ controlling structure primarily generates TZs at high frequencies, resulting in a further bandwidth enhancement in the stopband. The lumped circuit of the proposed BPF is first constructed, and rigorous design formulas are provided to assist in constructing the proposed design. After schematic optimization, the second step involves layout optimization and simulation based on the specific IPD process. Experimental results mounted on a printed circuit board demonstrate that the bandwidth spans from 3.3 to 4.2 GHz with an IL of only 2.0 dB at the center frequency. Additionally, this BPF achieves impressive sideband suppression, exceeding 18 dB in the 0–1.7 GHz range and 30 dB in the 9–15 GHz range. Remarkably, the BPF is exceptionally compact with only 0.5 mm × 1.0 mm (0.006λc × 0.012λc). The proposed BPF exhibits outstanding performance with minimal IL and extensive sideband suppression at such a compact size based on the IPD technology. [ABSTRACT FROM AUTHOR]

A low‐loss miniaturized bandpass filter is presented using 3D glass‐based RDL packaging technology. A new topology consisting of one modified Pi‐section and one modified T‐section is introduced to generate three transmission zeros which can achieve the high out‐of‐band rejection. A combination of 2D planar inductors and high‐Q 3D inductors is used to achieve low insertion loss and minimize the filter size. In addition, one grounded resonator at input terminal is introduced to generate an extra transmission zero in the low end. The proposed bandpass filter covering 3.3–4.2 GHz is fabricated with a compact size of 1.6 mm × 0.8 mm × 0.25 mm. It exhibits an insertion loss of less than 1.0 dB at a center frequency of 3.75GHz and a return loss of better than 14 dB. The proposed design has a 3 dB fractional bandwidth of 37.6%. Its out‐of‐band rejection is better than 20 dB at the low frequency band from DC to 2.0 GHz and better than 19 dB at the high frequency band from 5.0 to 9.0 GHz. The simulated and measured results of the proposed BPF are in reasonably good agreement. [ABSTRACT FROM AUTHOR]

A compact bandpass filter (BPF) with wide stopband performance is proposed and implemented on Si‐based integrated passive device (IPD) technology. A modified topology consisting of a novel Pi‐section and two capacitors are introduced in this BPF. The Pi‐section topology can achieve a band‐pass performance and generate four transmission zeros out‐of‐band. These two capacitors can improve the in‐band matching and also widen the stopband. The proposed BPF with a compact size of 1.0 mm × 0.5 mm × 0.3 mm is fabricated using Si IPD technology and measured by on‐wafer probing. It shows that the insertion loss is less than 1.75 dB, the return loss is better than 18 dB in the 5G band, and the upper stopband suppression level is better than 17.5 dB up to 18 GHz. The simulated and measured results of the proposed BPF are in reasonably good agreement. [ABSTRACT FROM AUTHOR]

A miniaturized bandpass filter (BPF) with low insertion loss based on a modified T‐section and a grounded transmission‐zero resonator is proposed. The novel T‐section consists of two resonators, which can achieve the bandpass performance with two transmission zeros (TZs) in the upper band. The grounded transmission‐zero resonator can generate an extra transmission zero in the lower band. Therefore, high frequency selectivity can be achieved by the above three transmission zeros near the passband. The proposed BPF can achieve an insertion loss of 0.8 dB and a return loss of 22 dB covering 3.3–4.2 GHz, and the upper‐stopband attenuation is better than 20 dB up to 12.5 GHz (3.3f0). The proposed BPF with a miniaturized size of 1.2 mm × 0.5 mm × 0.3 mm have been fabricated using Si‐based integrated passive devices (IPDs) technology and measured by on‐wafer probing. The simulated and measured results of the proposed BPF are in reasonably good agreement. [ABSTRACT FROM AUTHOR]

In this letter, a miniaturized bandpass filter (BPF) with controllable transmission zero (TZ) based on one lumped T‐section is proposed. To enhance rejection in the BPF, a modified T‐section circuit is introduced to generate a controllable TZ that can be readily adjusted by the LC values. To validate the performance, the proposed BPF is fabricated using integrated passive device technology on silicon. The measurement results show that the achievable bandwidth covers 2.4–2.5 GHz, with an insertion loss less than 2.6 dB and a measured return loss less than −15 dB. The fabricated BPF has a compact size of 1.3 mm × 0.8 mm (i.e., 0.0113 λ0 × 0.0069 λ0). The simulated and measured results of the BPF are in reasonably good agreement. [ABSTRACT FROM AUTHOR]

This letter proposes a miniaturized integrated passive device (IPD) bandpass filter (BPF) design with high out‐of‐band rejection for 5G applications. In this design, a novel topology based on the modified high‐pass filter cascaded with the modified low‐pass filter is introduced with two pairs of transmission zeros (TZs) at high and low frequencies. In addition, one grounded capacitor at the input is added to improve the suppression at high frequency end. The proposed BPF design is fabricated on silicon substrate. The measured insertion loss is around 3 dB and the return loss is <16 dB in the whole frequency range from 3.3 to 4.2 GHz for 5G applications. This proposed BPF achieves more than 20 dB sideband suppression at both stop bands from DC to 2.69 GHz and from 5.3 to 14 GHz. The fabricated device has a size of only 1 × 0.7 × 0.2 mm. [ABSTRACT FROM AUTHOR]

A miniaturised integrated passive device (IPD) balun design with low insertion loss and balanced amplitude and phase is proposed for Wi‐Fi/Bluetooth applications. In this design, a novel topology based on the modified T‐type filter structure is introduced to offset the parasitic and coupling effects that cause poor balance in IPD design. The proposed balun design is fabricated on a GaAs substrate. The measured insertion loss is lower than 0.9 dB and the measured return loss is >16 dB in the frequency range of 2.2–2.9 GHz. The measured results of amplitude and phase show rather minor imbalances, which are lower than ±0.67 dB and ±1.8° respectively. The fabricated device size is 0.9 mm × 0.6 mm only. [ABSTRACT FROM AUTHOR]

This letter proposes a novel compact ceramic cavity bandpass filter with surface silver coating and air coupling apertures. It is constituted of a sextuple‐mode ceramic cavity as the main resonator, two single‐mode cavities to connect the sextuple modes transversely with source and load, and two single cavities to suppress higher harmonics. This proposed filter has the advantages of compact size, wide band, low insertion loss, high selectivity, wide spurious‐free window, as well as coplanar source and load interfaces. There are no blind holes in the filter, which is beneficial for improving the machining accuracy. One prototype filter operating at 3.5 GHz is fabricated and measured. The minimum insertion loss in the passband is 0.65 dB. The inherent spurious mode of the sextuple‐mode resonator at around 1.2fC (fC center frequency) is suppressed under −30 dB. The measured and simulated results are in good agreement. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A compact low loss wideband diplexer is introduced by using stacked 2D and 3D structures through 3D advanced packaging and through glass vias (TGV). An inductor is designed by using stacked 2D and 3D structures to reduce the coupling effect between adjacent 2D inductors located in the same layer. It can greatly improve the Q factor yet minimize the chip size. This low loss, small size diplexer is developed by virtue of a modified topology and the proposed stacked 2D and 3D structures. The designed diplexer with a compact size of 1.6 mm × 0.8 mm × 0.25 mm is fabricated using 3D glass-based advanced packaging technology and measured by on-wafer probing. The measured results indicate that it achieves an insertion loss less than 0.8 dB and 0.9 dB and an isolation better than 20 dB and 17.5 dB in the bands of 0.699 GHz-0.960 GHz and 1.71 GHz-2.69 GHz, respectively. In comparison with the previously reported designs, the proposed diplexer shows the superior advantages of smaller size and lower insertion loss. [ABSTRACT FROM AUTHOR]

A compact bandpass filter with low insertion loss and high selectivity is presented using 3D glass-based IPD technology. A modified asymmetric π structure is introduced to generate three poles to achieve wide bandwidth and low insertion loss. In order to achieve better selectivity and higher out-of-band rejection, the introduced modified asymmetric π structure is adopted to generate two controllable transmission zeros on both sides of the passband. Compared to the traditional π structure, the modified π structure does not require the design to be completely symmetrical, thereby providing the filter design greater flexibility. High-Q 3D inductors based on 3D glass-based technology are utilized to achieve lower insertion loss. The proposed bandpass filter, which covers the band of 2.4–2.9 GHz, is fabricated with a compact size of 1.6 mm × 0.8 mm × 0.35 mm. The measured results show that it can achieve an insertion loss less than 1.6 dB and a return loss better than 15 dB in the passband. Its out-of-band rejection is better than 24 dB from DC to 1.89 GHz and from 3.7 GHz to 10 GHz. The simulated and measured results of the proposed BPF are in reasonably good agreement. [ABSTRACT FROM AUTHOR]

A novel T-type topology is proposed for the first time to generate a pair of transmission zeros (TZs), enabling a wide range of resistive band rejection within a specific range. The working mechanism is elucidated through its even- and odd-mode equivalent circuits, and the design process is outlined. Moreover, an enhanced third-order high-pass filter is integrated with the T-type circuit to form a bandpass filter (BPF). This proposed BPF is fabricated using on-chip integrated passive device (IPD) technology. The measured and simulated results confirm its performance. Notably, the proposed IPD BPF has fractional bandwidth (FBW) of only 16.3 % and an insertion loss (IL) of 1.8 dB within the passband, thereby making it promising for narrowband applications. In addition, its compact size makes it suitable for Wi-Fi applications. [ABSTRACT FROM AUTHOR]

A miniaturized bandpass filter (BPF) with ultrawide-stopband and high selectivity performance is proposed by virtue of glass-based integrated passive devices (IPD) technology. The proposed BPF consists of two modified second-order units and an impedance inverter. In the modified second-order units, two capacitors are added to the traditional second-order Chebyshev bandpass filter, which can generate two additional transmission zeros locating in the lower and upper bands, respectively. Moreover, these two modified second-order units are cascaded to improve the selectivity and achieve the ultrawide-stopband of the proposed BPF. In addition, the cascaded impedance inverter is introduced to further improve impedance matching of the proposed BPF. The proposed BPF is fabricated using glass-based IPD technology and measured by on-wafer probing. The fabricated BPF has a compact size of 1.0 mm × 1.0 mm × 0.35 mm. The measured results show that the fabricated BPF can cover the wide operating band from 3.3 GHz to 5.0 GHz with an insertion loss of 1.4 dB, a return loss better than 17.5 dB in the passband, and an upper stopband suppression better than 21.6 dB up to 43.5 GHz (10.48 f 0). In addition, the fabricated BPF can achieve a good frequency selectivity with a rectangular coefficient of 1.33. The simulated and measured results exhibit good agreements. [ABSTRACT FROM AUTHOR]

A novel on-chip bandpass filter (BPF) design with controllable transmission zeros (TZs) for high out-of-band rejection is proposed using the hybrid coupling technique. The proposed hybrid coupling filter consists of two symmetrical hybrid coupling spiral structures where the mutual electric and magnetic couplings are introduced to generate two TZs in the high frequency band. The center frequency, bandwidth, and transmission zero position of the proposed filter can be well controlled. To illustrate the principle of this configuration, an equivalent circuit with odd- and even-mode analysis is discussed. Moreover, another transmission zero in the low frequency band can be further generated by loading a quasi-distribution structure. The proposed hybrid coupling filter is fabricated using commercial high resistance silicon technology. The measured results show that the proposed filter can achieve a 3 dB bandwidth from 1.85 to 2.33 GHz, which indicates a fractional bandwidth of about 26 %. In addition, more than 40 dB of suppression is achieved from 3.15 to 5.55 GHz. A return loss of 29 dB and a minimum insertion loss of 2.5 dB are achieved at the center frequency with a minimized size 1.6 mm × 0.8 mm. The simulated and measured results are in good agreement. [ABSTRACT FROM AUTHOR]

Inductors that are widely used in wideband filter designs could result in large filter size and high insertion loss. A novel design method using admittance matrix based on direct circuit implementation is introduced for wideband bandpass filters. Firstly, a frequency transformation is performed on cross-couplings to realize the conversion between inductor and capacitor, thereby reducing usage of inductors. Moreover, by virtue of an enhanced resonator (type I), an approach of adding extra transmission zero is proposed to improve the out-of-band rejection without any additional usage of inductors. Thirdly, based on the frequency transformation, another enhanced resonator (type II) is introduced to further improve the frequency characteristics without compromising usage of inductors. Finally, by cascading the enhanced resonators of type I and type II, a novel filter can be constructed. This novel filter is designed and fabricated using a glass-based integrated passive device (IPD) technology. The measurement results are highly consistent with the simulation results. It is shown that the proposed design method can reduce the filter size and thus improve the chip integration. It enriches the freedoms during the filter design. [ABSTRACT FROM AUTHOR]