Search

Balanced dielectric resonator (DR) filters with multiple reconfigurable passbands are proposed in this article. Based on the field distributions of two pairs of orthogonal degenerate modes, quad-mode differential-mode (DM) operations are achieved by the specific probe feeding structure. More importantly, the four modes are flexibly controlled by different inserted screws and the detailed principle is illustrated for reconfiguration. For demonstration, a dual-band balanced filter with independently frequency-tunable passbands and a quad-band one with selectable number of passbands are fabricated and measured. Good agreement between the simulated and measured results is observed. The exhibited low DM loss, high common-mode (CM) rejection, and independent tuning abilities verify the proposed method in miniaturized reconfigurable filter designs.

A dual-band coaperture monopolar antenna with a very low profile is investigated in this communication. A novel cross-layer folded structure is proposed to construct a single-band monopolar antenna in the lower band. It can provide enough space for another higher band section to be integrated together without extra profile. Meanwhile, by adding a high-frequency radiation element to the reserved space, a dual-band coaperture antenna with independent frequency control is obtained. Moreover, by exciting TM01 and TM02 modes in both bands, the proposed antenna can achieve a relatively large impedance bandwidth of 10.9% in the lower band and 14.6% in the upper band with a thickness of 3.14 mm. Stable monopole-like radiation patterns are achieved within the two bands and the gains in the lower and upper bands are 5.2–5.8 and 3.7–5 dBi, respectively. Compared with other works, the proposed antenna features its low-profile and independent band performance.

Dual-mode filtering switches using hybrid microstrip-cavity structures are proposed in this article. TE101 and TE011 modes of the cavity act as the resonant modes to obtain a dual-mode filtering response. The microstrip line integrating the control circuit is employed as the feeding network. In the ON-state, the diode of the control circuit is reverse biased. Based on the electromagnetic (EM) coupling theory, the two modes are excited to attain filtering performance, and the loss of the diode is significantly alleviated. When the diode is forward biased, the two modes are suppressed and isolation in the OFF-state is realized. Benefiting from the hybrid microstrip-cavity configuration, the coupling between source/load and resonator is flexible to control. Single-band and dual-band filtering switches are constructed. The dual-band filtering switch processes high selectivity passband response in the ON-state, the insertion losses are 0.4 dB, and three transmission zeros are distributed in the two bands. In the OFF-state, the isolations of the two bands are below 37 and 30.7 dB, respectively. Thus, the dual-mode filtering switches maintain high- $Q$ features as the cavities. Moreover, they have multifunctionality and flexibility compared to the conventional cavity structures fed by probes and waveguides.

Compact dual-band diplexers with single-ended and balanced ports based on quad-mode dielectric resonators (DRs) are proposed in this article. Two pairs of orthogonal degenerate modes are employed not only to form four frequency channels but also to achieve high isolation of dual-band diplexer. Quad-mode field distributions and couplings with input and output probes are analyzed in detail to realize dual-band diplexer characteristics. Due to the couplings of straight probes and sharing of common input and output quad-mode DRs, multiport junctions in conventional designs are saved, and the number of resonators is remarkably reduced. Therefore, miniaturized sizes are obtained in both single-ended and balanced designs. For verification, Sub-6-GHz dual-band diplexers with single-ended and balanced ports are fabricated and measured. With only two cuboid DRs and three sets of probes, low losses in all four bands and isolations that better than 34 dB are achieved in both two designs. Moreover, the common-mode (CM) suppression of the balanced diplexer is better than 50 dB. The exhibited high in- and out-of-band performance of the diplexers demonstrates the proposed method.

A 60 GHz CMOS Doherty power amplifier (Doherty PA) is investigated in this work. Due to the absence of ideal current source in CMOS technology, a dual-adaptive biases scheme is utilized to realize Doherty operation. The efficiency enhancement is realized by providing the optimum biases to the carrier and peaking amplifiers according to the input power level. The input matching network is designed using adaptive power distribution network (APDN). Therefore, the RF power loss at low power level is minimized. The load modulation is realized without using phase-offset lines and any bulky impedance inverters such as transformers and inductors. As a result, optimum load impedances are achieved at each power levels while the chip size is very compact. Meanwhile, the layout sensitivity and on-chip EM problems can be mitigated. The proposed Doherty PA is designed and fabricated in 65 nm CMOS process. The measured result reveals 16.8 dBm power at output 1-dB gain compression point (OP $_{\text {1dB}}$ ). 17.5% and 9.5 % power added efficiency (PAE) are achieved at $\text {OP}_{\text {1dB}}$ and 6-dB output back-off level.

This brief presents a synthesis method to design compact low temperature co-fired ceramic (LTCC) filtering balun with harmonic suppression. To achieve wide upper stopband, the design equations are driven based on the schematic. Benefiting from the three-port synthesis method and the flexible 3-D layout on LTCC technology, the coupling matrices at the second and third harmonics are manipulated to achieve the harmonics suppression without extra circuits. Meanwhile, the coupling elements of the passband can keep their desired values. A LTCC filtering balun is designed and implemented for demonstration. A 20 dB stopband rejection from $1.2{f} _{0}$ to $4.1{f} _{0}$ is observed. Good agreement between simulated and measured results verifies that the proposed method is suitable and the LTCC technology is reliable for wide stopband filtering balun designs.

Filtering baluns are proposed based on the hybrid cavity-microstrip structures in this article. The cavity acts as the resonator to obtain the filtering response. In the meanwhile, the microstrip feeding networks are used to excite multiple modes and achieve the balun characteristics simultaneously. The coupling mechanism between the slots and the cavities is utilized to analyze the single- and dual-band filtering baluns. Therefore, by combining the benefits of the cavities and the microstrip lines, multifunctional filtering baluns are realized. Besides, to reduce the volume and insertion loss further, a filtering balun based on the dielectric cavity-microstrip structure is presented and designed. It possesses high selectivity passband response, magnitude imbalance of 0.075 dB, and phase difference of 180° ± 0.2°. It is much smaller than that fed by the waveguide. On the other hand, it is easy to integrate with other components and robust in structure compared to that fed by the probe. Thus, the proposed hybrid structure not only maintains the high performance of the cavity but also has the flexibility of the planar circuit.

This paper presents a dual-band co-aperture monopolar antenna with a very low profile. A novel cross-layer folded structure is first constructed to radiate in the lower band. Meanwhile, it provides enough space for another higher-band section. Then, a via-loaded circular patch is added to the reserved space, and the dual-band co-aperture antenna with independent band performance is obtained. By employing two pairs of similar modes in the two bands, the proposed antenna achieves a relatively large bandwidth of 10.9% in the lower band and 14.6% in the upper band with a thickness of 3.14 mm. Stable conical beam are achieved within both bands and the gains in the lower and upper bands are 5.2-5.8 and 3.7-5 dBi, respectively.

Two novel high selectivity balanced-to-unbalanced filtering power dividers using ring resonators are proposed. The even-/odd-mode analysis method is applied to obtain the design equations at the operating frequency. The ring resonators can bring two transmission zeros in each side of the passband for the differential mode for the filtering power divider (structure I). Moreover, the three-quarter wavelength transmission lines are applied to produce the additional two transmission zeros of differential mode for structure II, which can further improve the differential-mode harmonic suppression and common-mode suppression. Two fabricated prototypes with 4-dB bandwidths of 11.2% and 11.6% are designed and measured to prove the proposed methods. All the structures show good performances for differential-mode power division and common-mode suppression.

This paper presents a balanced dual-band filter using dual-mode dielectric resonators. A pair of HEH 11 degenerate modes is employed to construct dual-band differential-mode operation based on their symmetrical field distributions. Besides, the orthogonality of these two modes is utilized to independently design two passbands using cross-shaped slot. With only two DRs and two pairs of probes, low loss balanced dual-band response and high level common-mode rejection could be achieved at the same time. A balanced dual-band filter centered at 3.4 and 3.6 GHz is implemented for demonstration. The exhibited good agreement between simulated and measured results supports the proposed idea.

In this paper, a Doherty power amplifier (DPA) in 65 nm CMOS process at 60 GHz is presented. In the proposed design, both the gate biases of carrier and peaking amplifiers are adaptively controlled according to input power levels. Different bias control schemes are applied for the carrier and peaking amplifiers respectively to achieve efficient Doherty operation and improve efficiency. Power detectors are applied to achieved the dynamic bias voltages and consumes very low power. By combining active load modulation and the adaptive biases, both the back-off and saturation power added efficiencies (PAEs) of the DPA are enhanced and the gain compression point is extended. Simulated results show that the 20% saturation PAE and 13% 6-dB back-off PAE are achieved, and the output 1-dB gain compression point (OP1dB) is around 17 dBm.

This paper presents single-and dual-band filtering power amplifiers (FPA). In single-band FPA, a bandpass filter (BPF) using discriminating coupling is proposed to be utilized as the output matching network (OMN). By analyzing coupling matrix of BPF, impedances of the OMN at fundamental mode and harmonic are controlled independently. In dual-band FPA, a dual-band filtering network synthesis technique is proposed. It includes two steps: building impedance transformation network (ITN) with transmission zeros pair (TZP) to generate dual-band filtering performance and utilizing synthesis technique to obtain the structure parameters by making the fundamental and the second harmonics matched at the two passbands. For demonstration, a single-band FPA with wide bandwidth of 31.1% is implemented and measured. Also, the dual-band FPA exhibits both high bandpass selectivity and good PA performance with maximum power added efficiencies (PAEs) of 70.2% and 69.2% at 1.78 and 2.45 GHz, respectively.

Patch antennas with multiple feeds are proposed in this paper. The antennas consist of a traditional square patch and feeding probes that are set in a line orthogonal to the polarization direction. In addition to radiating EM energy just like the conventional antennas, the proposed multi-port antennas can also realize on-antenna power combining without power combiner. Thanks to this, high-line losses and large system size caused by extra power combiner can be avoided. Moreover, since the location and the number of ports have a limited effect on the antenna performances, flexible feeding strategies can be chosen in different applications. For demonstration, four patch antennas with a different number of ports (one port, two ports, three ports, and four ports) are designed at the center frequency of 1.5 GHz. Compared with the traditional one-port patch antenna, the proposed three multi-port patch antennas can achieve nearly the same antenna performance, including bandwidth, polarization, efficiency, and radiation pattern. Besides, one-port antenna and two-port antenna integrated with a two-way power amplifier are designed and measured, respectively. Then, they are compared to further prove the proposed power combining method in multi-port antennas.

In this paper, a compact filtering rat-race coupler implemented in low-temperature co-fired ceramic (LTCC) technology is presented. In order to reduce the dimensions, the schematic and the coupling topology of a planar filtering rat-race coupler are first studied and then simplified to fit the 3-D multilayer LTCC structure. An eight-line spatially symmetrical coupled structure is, therefore, proposed to obtain the required coupling topology between resonators. Thus, the filtering rat-race coupler can be constructed only by using four resonators, which is only half that of the planar one. Consequently, the size could be reduced substantially. For validation, a design example centered at 3.5 GHz is simulated, fabricated, and measured. All the measured results are in good agreement with the full-wave simulation results. Besides, the size of the circuit is only 3.8×4×2.1 mm3, which demonstrates that by employing the eight-line spatiallysymmetrical coupled structure, the proposed rat-race coupler obtains good performance and compact size.

This work presents the performance test results for novel two-piece ultra-thin vapor chambers with a thickness (t) of 0.38 mm, 0.48 mm and 0.58 mm, having a vapor duct thickness (h) of 0.15 mm, 0.25 mm, and 0.35 mm, respectively. These ultra-thin vapor chambers simply comprise a top plate etched with arrayed pillars as the condenser and a mesh-wicked bottom plate as the evaporator and liquid path. The inner surface of the top plate contains cross parallel vapor ducts configured by aligned pillars for vapor spreading all over the vapor chamber. The pillars provide strong structural support, an enlarged condensation area, and a direct shortcut for liquid return. Compared to traditional vapor chambers, the novel ultra-thin vapor chambers have the advantages of simpler structure, easier manufacturing process, lower cost, superior anti-compression ability, and better thermal performance. They keep excellent structural integrity at a footprint of 140 mm × 80 mm. Cooled by natural convection, the vapor chamber resistances (Rvcs) are measured for different hs at different filling ratios (γs). Capillary blocking is observed for h = 0.15 mm and 0.25 mm at γ larger than 1.0, but it does not appear for h = 0.35 mm even with considerable over-charge. Although capillary blocking may slightly raise Rvcs, it can be avoided by suitable under-charging. Except for cases with significant over-charge, Rvcs are similar for h of 0.15 mm to 0.35 mm at heat loads less than 15 W due to the low vapor resistances at low mass flow rates. At heat loads of about 14 W, the minimum Rvcs of unblocked ultra-thin vapor chambers are about 0.25 K/W to 0.3 K/W, greatly superior to the value of 0.88 K/W of a 0.5 mm-thick copper plate.

This brief presents a filter-integrated high-efficiency class-F power amplifier (PA). The hybrid cavity–microstrip filtering circuit is employed not only to realize output impedance matching and the third-harmonic manipulation but also to provide high-selectivity bandpass responses. To fulfill the requirements of high-efficiency class-F PAs, cavity resonators and microstrip feeding structures are involved, and their benefits are fully exploited. The metal cavity resonator features a high $Q$ value and, thus, low loss in the passband, resulting in high efficiency. Moreover, metal walls of cavities act as heat sink for the transistor. The microstrip feeding structures are used to improve the skirt selectivity and manipulate the third harmonic. Moreover, it features easy integration with the transistor, and thus, the transition between cavity and microstrip lines is eliminated. The hybrid filter is characterized based on filter synthesis theory. Complex impedance conversion analysis is carried out to guide the impedance transformation from 50 $\Omega$ to a complex one desired by the transistor. For demonstration, a filtering PA operating at 2.4 GHz is designed and measured. It exhibits both high-selectivity bandpass responses and good PA performance with maximum power-added efficiency of 70.9% at 40.8-dBm output power.

This paper presents a compact microwave out-of-phase filtering power divider in low-temperature co-fired ceramic (LTCC) technology. The proposed device is composed of three resonators and an isolation resistor. One resonator is symmetrically coupled with the other two by employing multiple broadside coupled lines. Utilizing the transmission line theory, the magnitude and phase characteristics are addressed. Theoretical analysis indicates the proposed circuit provides two signal paths with bandpass responses and 180° phase difference. Also, the realization of the isolation between two output ports is analyzed. For validation, a filtering power divider with out-of-phase outputs is designed, fabricated, and measured. It occupies a compact area of $3.1 \times 3.2 \times 1.6$ mm3. Comparisons of the measured and simulated results are presented to verify the theoretical method.

A low-temperature co-fired ceramic (LTCC) filtering power divider with harmonic suppression is presented. It is composed of three resonators and one resistor. By using 3D technology, the two output resonators are symmetrically coupled to the input resonator to obtain the power splitting response. Each splitting path is composed of two resonators to achieve the filtering response. The resistor for isolation is located on the top layer and connected to the two output ports by vertical strips on the side walls. The broadside couplings between resonators produce required passband and stopband. A compact filtering power divider with the core size of 0.122λ g × 0.1λ g × 0.059λ g is implemented. Good filtering, power splitting and isolation performance are achieved. What is more, the second harmonic is successfully rejected below 20 dB without any extra circuit.

A compact low temperature co-fired ceramic (LTCC) bandstop filter (BSF) with controllable bandwidth is presented in this paper. Compared with the conventional method, the internal coupling between resonators is introduced in the structure to split one zero into two, namely transmission zeros pair (TZP). Then the bandwidth is flexibly controlled by adjusting the internal coupling strength. Besides, multiple transmission poles (TPs) are generated to enhance the roll off while maintaining the stopband performance. For demonstration, a LTCC wideband BSF is implemented and measured. Both TZP and multiple TPs are observed with compact circuit size. Good agreement between the simulated and measured results verifies the proposed method.

A filtering balun based on multi-mode rectangular cavity is proposed in this paper for the first time. The printed circuit board (PCB) microstrip lines cooperated with coupling slots are utilized as feeding structures. The $TE_{101}$ mode is employed to construct the passband while the $TE_{011}$ and $TM_{110}$ modes are used to generate two out-of-band zeros. Besides, by analyzing the electromagnetic field distributions, the balun characteristic at the two outputs are achieved due to the antisymmetrical arrangement of the output feeding lines. For demonstration, a second order cavity filtering balun is designed and measured. Both good filtering response and balun characteristic are observed in the measurement, which validate the proposed method.

Background Our aim was to retrospectively analyze the relationships between circulating tumor cells (CTCs) and the development of breast cancer, for elucidating the role of CTCs in breast cancer. Methods A total of 107 female patients with primary breast cancer and 48 matched healthy female volunteers were recruited. After blood collection, isolation of peripheral blood mononuclear cells (PBMC) was performed followed by the detection of cytokeratin 19 positive (CK19+) and CD44+/CD24−/low cells, as well as estrogen receptor (ER), progesterone, and CerbB2. Data were analyzed with the SPSS 20.0 software. Results None of the 48 volunteers were detected with CK19+ cells in their PBMC, while in 77 patients, 72% of 107 female patients with primary breast cancer, the CK19+ cells were detected. CK19+ could also be detected among patients in each grouping by different clinical staging and lymph node metastasis, with statistical differences (all P 0.05). Conclusions Both CTCs and tumor stem cells (TSCs) could be detected in the PBMC of breast cancer patients; besides, positive expression rate of CTCs might be obviously associated with the clinical stage and metastasis. Positive relationship of TSCs and the clinical stage of breast cancer was also proved in this study.

In this paper, a new discriminating coupling mechanism, which is realized by choosing suitable coupling region between the feeding lines and resonators, is proposed to suppress the unwanted resonance modes without affecting the desirable operating modes. Utilizing such a coupling mechanism, two low-temperature cofired ceramic (LTCC) bandpass filters (BPFs) are designed operating at microwave and millimeter-wave bands. One BPF realizes a wide stopband, since the third and fifth harmonics are suppressed by the discriminating coupling. The other one is an oversized 60-GHz BPF with the fundamental mode suppressed by the discriminating coupling. Due to the multilayer characteristics of the LTCC techniques, the circuit layout can be controlled flexibly to realize desirable discriminating coupling. The two filters are theoretically analyzed and implemented. Good agreement between the simulation and the measurement validates the proposed method.

This paper presents some multi-function microwave components based on implantable filters. It is found that some bandpass filters (BPFs) have the properties of ±K-inverters, meaning that they can be utilised to replace 90° or 270° transmission lines in passive microwave components such as in-phase and out-of-phase power dividers and rat-race couplers to realise both filtering and power-splitting functions. The ±K-inverter properties also mean that the proposed filters can be employed as impedance transformers in output-matching networks (OMNs) of power amplifiers for efficiency improvement and harmonic suppression. As a demonstration, some power combining and dividing components and power amplifiers are implemented based on the implantable filters, which exhibit dual functions, good performance and compact size.

This paper presents three kinds of multifunctional devices using discriminating coupling. The designs of filtering power divider (FPD), filtering balun as well as filtering power amplifier (PA) are achieved to avoid cascaded mismatch and reduce the overall circuit sizes. Theory of discriminating coupling is analyzed to control the harmonics of the devices. Thus, the fundamental and harmonic responses can be designed respectively. For demonstrations, a FPD and a filtering balun using low temperature co-fired ceramic (LTCC) technology are fabricated for the wide stopband. Meanwhile, a filtering PA in printed circuit board (PCB) process is realized for the efficiency and bandwidth enhancement.

This letter presents a filtering power divider using modified parallel coupled-line bandpass filter (BPF) with multiple coupling from source/load to resonators. This novel coupling topology includes additional coupling between source/load and non-adjacent resonators, namely, extra cross-coupling paths, for a better selectivity. Then less resonators are required to achieve the same stopband performance compared with conventional parallel coupled-line BPF with the same order. Three isolation resistors, instead of only one in the conventional power dividers, are used for flexible optimization of isolation. For validation, a three-order filtering power divider operating at 3.4 GHz is demonstrated with more than 14 dB in-band isolation. Three transmission zeros are generated at 2.02 GHz, 2.56 GHz and 4.34 GHz to achieve a better selectivity.

This paper presents a compact low temperature co-fired ceramic (LTCC) balun filter with the second harmonic suppression. It is composed of two half-wavelength resonators and three feeding lines. The 180° phase difference between two output ports is obtained owing to the out-of-phase characteristic at the two open ends of the half-wavelength resonator. By using discriminating coupling between feeding lines and resonators, the second harmonic is rejected. The coupling coefficient in the passband can be tuned to the desired value through the gap. A LTCC balun filter centered at 4.6 GHz is implemented. Good agreement between the simulated and measured results is observed. The stopband rejection below 34 dB is from 1.2f 0 to 2.6f 0 and the core circuit size is 3.3 mm × 2.7 mm × 1.6 mm or 0.122λ g × 0.1λ g × 0.059λ g .

Pose estimation problem of an object in real time is an important issue for robotic visual servoing (RVS). Many pose estimation schemes in RVS rely on an extended Kalman filter (EKF) that provides good accurate estimation. However, it may cause the estimation to become unstable because of nonlinear modeling uncertainties. While, smooth variable structure filter (SVSF) is a new method that is more robust to disturbances and uncertainties. In this paper, a novel pose estimate method is developed based on the EKF and SVSF. It is combined the accuracy of the EKF and the robustness provided by the SVSF that will lead to more accurate state estimates and improve robustness to modeling errors and uncertainties. The resulting algorithms are called the EKF-SVSF. The simulation results are provided to demonstrate the robustness and accuracy.