Bandwidth Improvement of MMIC Single-Pole-Double-Throw Passive HEMT Switches with Radial Stubs in Impedance-Transformation Networks

In this paper, we propose a new configuration for improving the isolation bandwidth of MMIC single-pole-double-throw (SPDT) passive high-electron-mobility transistor (HEMT) switches operating at millimeter frequency range. While the conventional configuration adopted open-stub loading for compensation of the off-state capacitance, radial stubs were introduced in our approach to improve the operational bandwidth of the SPDT switch. Implemented in 0.15 m GaAs pHEMT technology, the proposed configuration exhibited a measured insertion loss of less than 2.5 dB with better than 30 dB isolation level over the frequency range from 33 GHz to 44 GHz. In terms of the bandwidth of operation, the proposed configuration achieved a fractional bandwidth of 28.5% compared to that of 12.3% for the conventional approach. Such superior bandwidth performance is mainly attributed to the less frequency dependent nature of the radial stubs

An Integrated Edge and Fog System for Future Communication Networks

Put together, the edge and fog form a large diverse pool of computing and networking resources from different owners that can be leveraged towards low latency applications as well as for alleviating high traffic volume in future networks including 5G and beyond. This paper sets out a framework for the integration of edge and fog computing and networking leveraging on ongoing specifications by ETSI MEC ISG and the OpenFog Consortium. It also presents the technological gaps that need to be addressed before such an integrated solution can be developed. These noticeably include challenges relating to the volatility of resources, heterogeneity of underlying technologies, virtualization of devices, and security issues. The framework presented is a Launchpad for a complete solution under development by the 5G-CORAL consortium.This work has been partially funded by the H2020 collaborative Europe/Taiwan research project 5G-CORAL (grant num. 761586

Epidemiological trend in inflammatory bowel disease in Taiwan from 2001 to 2015: a nationwide populationbased study

Background/Aims Incidences of inflammatory bowel disease (IBD), ulcerative colitis (UC), and Crohn’s disease (CD), have been increasing in Asia. In this study, we report the relevant clinical characteristics and determined the epidemiological trend of IBD in Taiwan from 2001 to 2015. Methods A retrospective study was conducted to analyze data recorded from January 2001 through December 2015 in the registered database compiled by the National Health Insurance and provided by the Ministry of Health and Welfare, Taiwan. Results A total of 3,806 patients with catastrophic IBD illness were registered from 2001 to 2015 in Taiwan (CD, 919; UC, 2,887). The crude incidence of CD increased from 0.17/100,000 in 2001 to 0.47/100,000 in 2015, whereas that of UC increased from 0.54/100,000 in 2001 to 0.95/100,000 in 2015. The prevalence of CD increased from 0.6/100,000 in 2001 to 3.9/100,000 in 2015, whereas that of UC increased from 2.1/100,000 in 2001 to 12.8/100,000 in 2015. The male-to-female ratio in the study sample was 2.19 for CD and 1.62 for UC. The median age of those registered with CD was lower than that of those registered for UC: 38.86 and 44.86 years, respectively. A significantly greater increase in CD incidence rate was identified among 20 to 39-year-old compared with other age groups. Conclusions Using Taiwan’s nationwide insurance database, we determined that the number of patients with CD increased more rapidly during the study period than the number of patients with UC, especially among age 20 to 39-year-old, resulting in a decreased UC-to-CD ratio

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Dual-Band Power Amplifier Design at 28/38 GHz for 5G New Radio Applications

This paper presents the design of a dual-band power amplifier (PA) featuring similar performance at 28 GHz and 38 GHz. In the new radio (NR) of the fifth generation (5G) communication system, the inter-band carrier aggregation technique is commonly adopted for data rate enhancement. In such configuration, operation at both bands of the 5G frequency range 2 (FR2) spectrum is often necessary. The stacked-FET topology was adopted for mitigation of the gain roll-off with frequency to achieve similar performance at both frequency bands. Implemented in the commercial 0.15- $\mu \text{m}$ gallium arsenide (GaAs) pseudomorphic high electron mobility transistor (pHEMT) technology, the PA delivered a small signal gain of 18.5/18 dB, an output power at saturation (Psat) of 28.5/28.2 dBm, and a peak power-added efficiency (PAE) of 39%/36% at 28/38 GHz, respectively. The measurement results have demonstrated great potential of the proposed PA for 5G NR applications

Novel Low-Cost Power Divider for 5.8 GHz

This paper presents a new capacitive lump-free structure for power dividers using a printed-circuit board, while maintaining size reduction and physical isolation. The conventional lumped capacitors approach has self-resonant problem and cause worse S 22 and isolation at high frequencies. To overcome such technical issues, the coupled-line structures were introduced in the isolation network. After optimizing the distance between output ports and position of the isolation network, tuning the characteristic impedance and electrical length of transmission lines can decide the value of the lump resistor. The first example was designed at 1 GHz, and the resistor in the isolation network was 330 ohm, having 0.2-dB insertion loss and 19% total bandwidth, while maintaining 80-degree distance between split ports and 180-degree total length, providing 21% to 67% size reduction. The second example was designed at 5.8 GHz, which was five times greater than in past research, using an RO4003C substrate while maintaining a 0.24-dB insertion loss, 17% total bandwidth, and 0.06 dB amplitude imbalance, which was only 0.01 dB more than in recent research. Such superior performance is mainly attributed to the coupled transmission lines in the isolation network featuring a capacitive lump-free isolation network. Our data indicate that amplitude imbalance, bandwidth, and miniaturization are superior to any published data

Rigorous Analysis and Investigation of the Bandwidth Broadening Mechanism in a Compact Power Divider With Physical Port Isolation

This paper proposes a compact power divider with simultaneous physical port isolation and wideband operation based on the simple Wilkinson power divider (WPD) configuration. Rigorous analysis based on the even- and odd-mode bisected networks has been performed to investigate the relationship between the design parameters and the overall performance. Theoretical analysis revealed that the impedance and isolation bandwidth are directly related to the reflection coefficients of the even- ( $\Gamma _{\text {e}}$ ) and odd-mode ( $\Gamma _{\text {o}}$ ) bisected networks. Simultaneous broadening of the impedance and isolation bandwidth is possible through the optimum choice of design parameters which confines the trajectories of the $\Gamma _{\text {e}}$ and $\Gamma _{\text {o}}$ in the low constant-Q region on the Smith Chart. Experimental verification by the prototype designed at 1 GHz exhibited the widest overall system bandwidth (43.2%) and the lowest total electrical length (140.8°) as compared to the previous state-of-the-art WPD’s with physical port isolation

Bandwidth Improvement of Conventional Dual-Band Power Divider Using Physical Port Separation Structure

This paper presents the bandwidth improvement for dual-band power divider using complex isolation network while maintaining physical port separation. The conventional port-extended power dividers suffered from narrow system bandwidth. A rigorous analysis revealed that such problem was mainly due to the limited impedance bandwidth caused by the odd-mode bisected network. Moreover, the isolation bandwidth provided by the parallel L-C topology in the conventional approach was also limited. To overcome such technical issues, a serial L-C topology was proposed. Derivations of the impedance bandwidth through even- and odd-mode network analysis have been performed and optimal system bandwidth could be achieved when the reflection coefficients of the corresponding bisected networks exhibited minimum frequency dependence. Based on the theoretical analysis, simultaneous achievement of bandwidth broadening, size compactness, and physical port extension at both frequencies is possible with optimum combinations of the design parameters. The experimental results evidenced that other than the improvement in system bandwidth, the fabricated prototype featured low extra insertion loss, good isolation across the bands, and compactness in size while maintaining physical separation between the split ports compared with previously published works