Passive Device Technology Research Articles

On-chip Wi-Fi filter with FBW of 16.3 % and IL of 1.8 dB using novel T-type transmission zeros structure

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.

Miniaturized bandpass filter with ultrawide-stopband and high selectivity using glass-based IPD technology

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 (10.48f0). 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.

A miniaturized on‐chip BPF with low insertion loss and wide stopband based on integrated passive device technology

AbstractIn 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.

Compact wide single‐/dual‐band bandpass filter with equal inductance configuration in thin film IPD technology

AbstractHere, based on thin film integrated passive device (TF‐IPD) technology, compact ultra‐wideband (UWB) bandpass filter (BPF) and dual‐band bandpass filter (DBBPF) with equal inductance configuration are proposed. The configuration of equal inductance in a circuit contributes to reducing variables, simplifying the physical structure, and shortening the debugging time in the TF‐IPD design process. Despite all the inductors being equal in value, a wide passband can still be achieved. The measured results show that the centre frequency of UBW BPF is 11.43 GHz, and the 3‐dB fractional bandwidth (FBW) is 133% (3.87–18.99 GHz). And the 3‐dB FBWs of DBBPF centred at 6.5 GHz and 16.2 GHz are 92% (3.51–9.49 GHz) and 35% (13.33–18.98 GHz), respectively. The stopband of UBW BPF and DBBPF can be extended to 47.7 GHz and 44.8 GHz in sizes of 321 µm × 856 µm and 235 µm × 846 µm, respectively (excluding measuring pads).

A novel design method for wideband bandpass filters with fewer inductors

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.

Compact on-chip dual-band bandpass filter with wide out-of-band suppression based on hybrid coupling technique

A compact dual-band bandpass filter (BPF) with wide out-of-band suppression based on a hybrid coupling technique is proposed. This BPF consists of two hybrid spiral coupled resonators, in which the electrical coupling and magnetic coupling between resonators can generate two transmission paths for dual bands. This dual-band BPF has wide out-of-band suppression. Moreover, its passband frequency and bandwidth can be readily controlled. To illustrate its working principle, an equivalent circuit with even- and odd-mode analysis is presented. This dual-band BPF is fabricated using a silicon integrated passive device (IPD) technology. The fabricated dual-band BPF has a compact size of 1.6 mm × 0.54 mm × 0.23 mm and is measured. The measured results show that this dual-band BPF can generate two bands at 2.45 GHz and 6.15 GHz. In addition, more than 20 dB of suppression is achieved from 7.8 to 20 GHz (8.16f0). The simulated and measured results exhibit good agreements.

Compact IPD bandpass filter with wide upper stopband based on modified topology for 5G applications

AbstractA 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.

A simple miniaturized sub‐6‐GHz bandpass filter with wide upper stopband in gallium arsenide‐based integrated passive device process

AbstractA very compact three‐pole bandpass filter with wide upper stopband is proposed and implemented by gallium arsenide integrated passive device technology. By organizing inductor and capacitor in parallel with an LC series network, a dual‐frequency bandstop structure is constructed in the first step to achieve transmission zeros (TZs). Then, the lowpass capacitor network and highpass inductor network are wisely cascaded with the bandstop structure, thus to the realization of three‐pole bandpass filter with a wide upper stopband. Based on the even‐/odd‐mode analysis, theoretical equations for the in‐band resonances and out‐of‐band TZs are given. Then, one filter prototype centered at 4.4 GHz with 3‐dB fractional bandwidth of 45.5% is designed, fabricated, and measured. Both simulated and measured results indicate that the proposed filter exhibits a wide stopband rejection of 25 dB from 6.4 to 22.8 GHz as well as a very compact size about 0.026λg × 0.031λg.

The co-design of IPD high-selectivity diplexer and dual-band filter chips based on lumped element single-band filter

In this paper, a dual-band bandpass filter (D-BPF) and a diplexer are proposed. Their core structures are both a lumped element single-band bandpass filter (S-BPF) with dual transmission poles (TPs) and dual transmission zeros (TZs). For the D-BPF, based on this S-BPF, single-band impedance matching networks (S-IMNs) are used to form the second/third passbands. Two S-BPFs with different first reactance elements are used for the diplexer to achieve good isolation without T-junction. Finally, the D-BPF and the diplexer with center frequencies of 2.26/4.75 GHz and 2.3/5.75 GHz are fabricated by thin-film integrated passive device (IPD) technology. The physical size of the D-BPF chip is only 1.5 × 1.1 mm2, and the diplexer chip is 2.3 × 1.5 mm2. Measured results show they both have the advantages of good insertion loss, excellent impedance matching, high roll-off, and broad stopband rejection. The isolation of the diplexer is greater than 23 dB from 0 to 10 GHz.

Design of Hybrid Bandpass Filter Chips with High Selectivity and Wideband Using IPD and FBAR Technology

A novel hybrid bandpass filter (BPF) with wideband and high selectivity is proposed in this paper. The hybrid BPF is composed of two film bulk acoustic resonator (FBAR) cells and three lumped component resonators realized by the integrated passive device (IPD) technology. The ABCD matrix to S-parameters matrix method is used to calculate the frequency response of the BPF. Moreover, the expressions of transmission zeros (TZs) have been extracted. In the design process, an iterative design approach is proposed to improve the circuit and layout of the hybrid filter based on the packaged acoustic-electric hybrid simulation effect. Finally, two parts of the filter are packaged based on the flip-chip method, and two prototypes for the BPF are measured. The measured results of two chips with 3 dB fractional bandwidth of 13.7% and 15.8% are designed and fabricated, which verifies the validity of the proposed design principle.

Miniaturized IPD band pass filter with low insertion loss based on modified T‐section for 5G applications

AbstractA 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.

Real-Time Detection of Yeast Growth on Solid Medium through Passive Microresonator Biosensor.

This study presents a biosensor fabricated based on integrated passive device (IPD) technology to measure microbial growth on solid media in real-time. Yeast (Pichia pastoris, strain GS115) is used as a model organism to demonstrate biosensor performance. The biosensor comprises an interdigital capacitor in the center with a helical inductive structure surrounding it. Additionally, 12 air bridges are added to the capacitor to increase the strength of the electric field radiated by the biosensor at the same height. Feasibility is verified by using a capacitive biosensor, and the change in capacitance values during the capacitance detection process with the growth of yeast indicates that the growth of yeast can induce changes in electrical parameters. The proposed IPD-based biosensor is used to measure yeast drop-added on a 3 mm medium for 100 h at an operating frequency of 1.84 GHz. The resonant amplitude of the biosensor varies continuously from 24 to 72 h due to the change in colony height during vertical growth of the yeast, with a maximum change of 0.21 dB. The overall measurement results also fit well with the Gompertz curve. The change in resonant amplitude between 24 and 72 h is then analyzed and reveals a linear relationship with time with a coefficient of determination of 0.9844, indicating that the biosensor is suitable for monitoring yeast growth. Thus, the proposed biosensor is proved to have potential in the field of microbial proliferation detection.

Millimeter-wave wideband filtering on-chip antenna based on IPD technology

ABSTRACT A millimeter-wave wideband filtering on-chip antenna is proposed in this paper. Its operation frequency covers 32 GHz to 63 GHz, and the impedance fractional bandwidth reaches 63%. Based on the corner-fed patch antenna, the antenna in this work has a quasi-omnidirectional radiation pattern, and peak efficiency reaches 91.7%. By square slotting on the four sides of the patch and cross slotting on the center of the patch, the high-order mode is suppressed, which supports the wide operating frequency range with filtering characteristics. Split ring resonators are etched on the ground to strengthen filtering characteristics. Based on thin-film integrated passive device (IPD) technology, the proposed structure is applicable to the on-chip wideband and high-efficiency antenna array.

Compact filtering power divider for mm‐wave applications using integrated passive device technology

AbstractWe present a compact, filtering power divider (FPD) using integrated passive device technology (IPD) for mm‐wave applications. Our proposed FPD design integrates quarter‐wavelength coupled‐resonator bandpass filters with a Wilkinson power divider, using size reduction techniques. Coupled coplanar waveguides provide excellent coupling while occupying a small area, and metal‐insulator‐metal capacitors offer the required λ/4 phase shift without length extension. The center frequency of the filtering power divider/combiner (FPD/C) is located at 30‐GHz. We demonstrate our FPD design by fabricating four prototypes with parameter variations. The insertion loss, fractional bandwidth, and size of the FPD/C designed in this study are from 2.56 to 3.3 dB, from 9.67% to 19.4%, and from 0.592 to 0.220‐mm2, respectively. In addition, the return loss of all models at the center frequency is 28.5 dB or more, and the isolation is 16.6 dB or more.

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

AbstractIn 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.

A miniaturized low-loss absorptive bandpass filter using IPD technology

In this article, a highly miniaturized absorptive bandpass filter based on a novel topology is presented. The filter topology utilizes a resistor-loaded network to achieve absorptive characteristics while additional capacitive coupling between series resonators is introduced to enhance selectivity. The proposed filter with a center frequency of 2.5 GHz and a 3-dB bandwidth of 2800 MHz is implemented using a GaAs integrated passive device (IPD) technology, exhibiting a small die size (0.7 mm×1.13 mm), low loss in-band insertion loss (0.9 dB), high out-of-band rejection (8.8f0¿25 dB), and a wide low-reflection frequency range. The measurement results show good agreement with the simulations. These features show promising applications in highly integrated RF systems.

A Multilayered GaAs IPD Resonator with Five Airbridges for Sensor System Application.

This work proposes a microwave resonator built from gallium arsenide using integrated passive device (IPD) technology. It consists of a three-layered interlaced spiral structure with airbridges and inner interdigital structures. For integrated systems, IPD technology demonstrated outstanding performance, robustness, and a tiny size at a low cost. The airbridges were made more compact, with overall dimensions of 1590 × 800 µm2 (0.038 × 0.019 λg2). The designed microwave resonator operated at 1.99 GHz with a return loss of 39 dB, an insertion loss of 0.07 dB, and a quality factor of 1.15. Additionally, an experiment was conducted on the properties of the airbridge and how they affected resistance, inductance, and S-parameters in the construction of the resonator. To investigate the impact of airbridges on the structure, E- and H-field distributions of the resonator were simulated. Furthermore, its use in sensing applications was explored. Various concentrations of glucose solutions were used in the experiment. The proposed device featured a minimum detectable concentration of 0.2 mg/mL; high sensitivity, namely, 14.58 MHz/mg·mL-1, with a linear response; and a short response time. Thus, this work proposes a structure that exhibits potential in integrated systems and real-time sensing systems with high sensitivity.

Miniaturised wideband bandpass filter with good selectivity based on 3D heterogeneous integrated passive device technology

AbstractThe miniaturised wideband filter with good frequency selectivity and wide stopband is proposed, which is based on three‐dimensional (3D) heterogeneous integrated passive device technology. The proposed sixth‐order wideband bandpass filter is based on the magnetic‐coupling‐loaded highpass‐lowpass lumped topology and implemented by the 3D heterogeneous integration process, integrating GaAs‐based and Glass‐based micro‐nano‐scale processes together. Then, lumped inductors are designed in the Glass substrate with low dielectric loss tangent and realised by a three‐dimensional spiral structure. Therefore, the inductors have high quality factors and small sizes. The lumped capacitors are designed using the GaAs thin film process. Finally, a prototype with a 3‐dB fractional bandwidth of 42% is designed and fabricated at 3.875 GHz (f0). The upper‐stopband attenuation higher than 30 dB is extended to more than 5.15f0. It occupies only 0.014 × 0.018 λ02 (1.1 × 1.42 mm2), where λ0 is the free‐space wavelength at f0.

Simulation and discussion of typical radio frequency filters

The demand for filters is increasing as the frequency bands for 5G expand. RF filters become the segment with the largest market share of RF front-end chips. More crowded frequency bands, as well as thinner and lighter communication equipment, necessitate higher filter performance. In this paper, several technologies for the implementation of Radio Frequency filter are presented. Essentially three types are considered: (i) Lumped Element (LC) Filter and Integrated Passive Devices (IPD) technology; (ii) Acoustic Wave Filter; and (iii) a composite filter design that combines acoustic and IPD technologies. Benefits and drawbacks of these diverse configurations in terms of their technical performance and current applications are examined, and several models are presented and simulated using ADS software.

A Novel Compact, Wideband Four-Way Wilkinson Power Divider With an Improved Isolation Topology

This letter describes a novel lumped element circuit topology for the Wilkinson power divider (WPD) with compact and wideband performance using the bandpass matching network. The design method is inspired by even and odd modes analysis techniques, and the odd-mode circuit has the same grade as the even-mode one by an improved isolation network. The design equations for the proposed WPD are derived by analyzing the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Z$</tex-math> </inline-formula> parameter and the widest frequency response is obtained. The power divider is fabricated based on the GaAs-integrated passive device (IPD) technology that features a compact size of 1.5 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times$</tex-math> </inline-formula> 1.7 mm, with a relative bandwidth of 66.7%, good isolation greater than 20 dB, insertion loss (IL) less than 1.3 dB, and return loss (RL) better than 12.3 dB over a range of 1.3–2.6 GHz.