A miniature low‐power ultra‐wideband low noise amplifier in 0.18 μm CMOS

A 0.18‐μm CMOS low‐noise amplifier (LNA) operating over the entire ultra‐wideband (UWB) frequency range of 3.1–10.6 GHz, has been designed, fabricated, and tested. The UWB LNA achieves the measured power gain of 7.5 ± 2.5 dB, minimum input matching of ?8 dB, noise figure from 3.9 to 6.3 dB, and IIP3 from ?8 to ?1.9 dBm, while consuming only 9 mW over 3–10 GHz. It occupies only 0.55 × 0.4 mm² without RF and DC pads. The design uses only two on‐chip inductors, one of which is such small that could be replaced by a bonding wire. The gain, noise figure, and matching of the amplifier are also analyzed. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE , 2011.     

Hybrid Ku‐band low‐noise amplifier for mobile DBS active phased‐array antennas

In this article we present a two‐stage Ku‐band low‐noise amplifier (LNA) using discrete pHEMT transistors on non‐PTFE substrates for low‐cost direct broadcast satellite (DBS) phased‐array systems (patent pending). The vertical input configuration of the LNA lends itself to direct integration with input port of antenna modules of the phased array, which minimizes preamplification losses. DC decoupling between LNA stages is realized using interdigital microstrip capacitors such that the implementation reduces the number of discrete microwave components and thereby not only reduces the component and assembly costs but also decreases the standard deviation of such crucial parameters of phased‐array systems as the end‐to‐end phase shift of the amplifier and the amplifier gain. Using the proposed printed decoupling capacitors, a cost reduction better than 30% of the original costs has been achieved. Additionally, we present a hybrid design procedure for the complete LNA, including its input and output connectors as well as packaging effects. This method is not based on parameter extraction, but encompasses electromagnetic (EM) field simulator results which are further combined using a high‐level circuit simulator. According to the presented measurement results, the implemented Ku‐band LNA has a noise figure better than 0.9 dB and a gain higher than 20 dB with a gain flatness of 0.3 dB over a 5% bandwidth. © 2006 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2006.     

A systematic design of 1.5–9 GHz high power–high efficiency two‐stage GaAs PHEMT power amplifier

In this article, a systematic design approach for a Class‐A operated wideband power amplifier is presented. The power amplifier structure comprises of two transistors in the cascaded single stage traveling wave amplifier topology. A power amplifier was designed by using the systematic approach and fabricated with 0.25 μm GaAs PHEMT MMIC process. The amplifier has an area of 3.4 × 1.4 mm². Measurement results show that almost flat gain performance is obtained around 15 dB over 1.5–9 GHz operating bandwidth. In most of the band, with the help of a wideband load‐pull matching technique, the amplifier delivers P_o,sat and P_o,1dB of around 30 dBm and 28 dBm where the corresponding power added efficiencies are >50% and >36%, respectively. It is shown that the proposed design approach has the advantage of simple and systematic design flow and it helps to realize step‐by‐step design for the designers. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:615–622, 2014.     

High gain transmitarray antenna based on ultra‐thin metasurface

This article presents a bandwidth enhanced transmitarray (TA) antenna based on ultra‐thin metasurface (MS) for high gain operating at X‐band. The antenna consists of a three layers continuous flat structure and an aperture coupled microstrip antenna as the feed source. The relative phase shift of 360° is achieved by the unit cell design based on ultra‐thin MS, and the quasi‐spherical wave could be focused as plane wave when the wave goes through TA. The aperture coupled microstrip feed is designed with a bandwidth of 20.6%, and the bandwidth enhanced property of feed source will reduce the negative effect of elements mutual coupling on TA and increase the bandwidth of the TA antenna. The TA antenna gain increases from 8.25 to 18.98 dB and with a side lobe level of ?14.3 dB. Owing to the low‐profile and easy configuration, this kind of TA antenna has great potential, wireless communication.     

A new printed log‐periodic dipole array (PLPDA) antenna with bandwidth broadening and gain improving

A broader impedance bandwidth and higher gain printed log‐periodic dipole array antenna fed by half‐mode substrate integrated waveguide (HMSIW) is proposed in this letter for ultra‐wideband (UWB) wireless communication applications. The bandwidth of the reference antenna (5.1‐11.4 GHz) is expanded by 1.3 GHz by introducing a new resonance frequency with additional patches. Moreover; gain is enhanced over full band by attaching metal plate to narrow beam and adding directors to attract energy radiated by dipoles. A simulation analysis of the improved antenna with broader bandwidth of 4.1 to 11.7 GHz and higher gain is presented, along with a design procedure and experimental results. Measurement results are consistent with simulation results, which verifies the feasibility of this technique.     

Design and packaging of ultra‐wideband multiple‐input‐multiple‐output/diversity antenna for wireless applications

In this article, a new compact eight‐element three‐dimensional (3D) design of ultra‐wideband (UWB) multiple‐input‐multiple‐output (MIMO) antenna is proposed. For realizing polarization diversity, four elements of the MIMO antenna are oriented horizontally and four elements are arranged vertically. In the horizontal arrangement, the antenna resonating elements are placed orthogonally to each other, which reduces interelement coupling and offers a consistent link with the wireless systems/devices. The proposed antenna shows a bandwidth (S₁₁ ≤ ?10 dB) of 17.99 GHz (2.83‐20.82 GHz) and isolation larger than 15 dB in the resonating band. The proposed MIMO/diversity antenna performance parameters such as envelope correlation coefficient, diversity gain, and total active reflection coefficient are evaluated and presented. Furthermore, the unit cell of the MIMO system is simulated for the packaged environment and it is observed that the antenna housing does not affect the antenna performance.     

A state‐of‐art review on band‐notch characteristics in UWB antennas

Ultra‐wideband technology has experienced a rapid growth over the last decade for its contribution in different sectors of human society. Printed antennas are considered as preferred platform for implementing this technology because of its alluring characteristics like light weight, low cost, ease of fabrication, integration capability with other systems, etc. Antennas developed for ultra‐wideband applications are desired to have notch characteristics for avoiding interference with other existing radio communication systems. The techniques related to design and developments of printed band‐notched antennas are continuously upgraded for improving the antenna performance. In this article, a comprehensive review has been carried out on ultra‐wideband antennas with band notch characteristics proposed in around last decade. The band notched UWB antennas available in the literature have broadly been classified into five different categories based on their notch characteristics like single band‐notch, dual band‐notch, triple band‐notch, quad/multiple band‐notch, and reconfigurable/tunable band‐notch, respectively. This review exercise may be helpful for beginners working on ultra‐wideband band‐notched antennas and also such a review process is not available in the open literature to the best of author's knowledge.     

Compact slot‐loaded ultra‐wideband multiple‐input multiple‐output antenna with fractal‐inspired isolator

In this paper, a compact multielement ultra‐wideband (UWB) multiple‐input multiple‐output (MIMO) antenna is presented. The proposed antenna is designed by integrating novel technique of stub‐loaded slot, split square ring (SSR), and fractal‐inspired isolator. The antenna size is effectively miniaturized by implementing three‐sided symmetrical stub‐loaded Koch slot and square split ring. The impedance bandwidth is broadened by using small notched partial ground plane. The mutual coupling between the element is impressively reduced by isolating the structure with a Sierpinski fractal. As a result, the proposed antenna achieves a UWB response with a very broad impedance bandwidth of 3.1 to 19 GHz. Moreover, the proposed antenna obtains high peak stable gain and diversity gain of up to 10 dBi, lower group delay (<1 ns), and lower envelop correlation coefficient of <.01. The proposed antenna has electrically small dimensions of 35 × 53 × 0.8 mm. With this low‐profile configuration, the proposed antenna is especially a good candidate for portable UWB‐MIMO wireless communication system.     

Systematic design of 7‐to‐40‐GHz on‐chip mixer based on optimal impedance deviation coefficient

In this article, a 7‐GHz to 40‐GHz ultra‐wideband passive double‐balanced mixer MMIC using compact wideband Marchand balun (CWMB) is presented. The CWMB is analyzed and designed by introducing a novel optimal impedance deviation coefficient. A trade‐off between the needed bandwidth and the acceptable insertion loss in an ultra‐wideband passive‐doubly‐balanced mixer design can be made through introducing the optimal impedance deviation coefficient. Finally, to verify the proposed methodology, a compact wideband passive double‐balanced mixer monolithic microwave integrated circuit (MMIC) was designed and fabricated using a standard gallium arsenide (GaAs) pHEMT technology according to the process characteristics. Experimental results show that an ultra‐wideband mixer MMIC is realized from 7 GHz to 40 GHz (140% fractional bandwidth) with a measured conversion loss between 9.5 dB~12.5 dB (in‐band fluctuation less than 3 dB) and a LO‐to‐RF isolation larger than 34 dB. The measurement results are in good agreement with the simulation results.     

Design of a compact protrudent‐shaped ultra‐wideband multiple‐input‐multiple‐output/diversity antenna with band‐rejection capability

In this endeavor, a new multiple‐input‐multiple‐output antenna with a sharp rejection at wireless local area network (WLAN) band is designed and practically examined for portable wireless ultra‐wideband applications. The intended diversity antenna possess a small size of 15 mm × 26 mm and two inverted L‐strip are loaded over the conventional rectangular patch antenna to form protrudent‐shaped radiator that acts as a radiating element. The sharp band‐rejection capability at WLAN is established by incising the L‐shaped slits at the decoupling structure. More than ?21 dB isolation is accomplished for the complete working band (ie, 2.87 ‐17 GHz). Degradation in the antenna efficiency at the center frequency of band rejection corroborates the good interference rejection capability. The working capabilities of the intended antenna are tested by using the isolation between the ports, total efficiency, gain, envelope correlation coefficient, radiation pattern, mean effective gain, and total active reflection coefficient.     

A straightforward design technique for narrowband multi‐stage low‐noise amplifiers with I/O conjugate match

Low‐noise amplifier (LNA) designers often struggle to simultaneously satisfy gain, noise, stability, and I/O matching requirements. In this article, a novel design technique, tailored for two‐stage low‐noise amplifiers, is presented. The proposed design method is completely deterministic and exploits inductive source degeneration to obtain a two‐stage LNA featuring perfect input and output match together with low noise figure (NF) and a pre‐determined gain, including stability analysis. A novel flowchart is provided together with the corresponding design chart that contains gain, matching, and stability information, therefore addressing all key figures‐of‐merit of a linear amplifier. The design chart is easily implementable in commercial Electronic Design Automation software, to aid designers in the difficult task of selecting the appropriate source degeneration inductor value. The noise performance, on the other hand, is the best possible since the matching networks are designed to provide the input of the two Field Effect Transistors with the optimum termination for noise. The design method is validated with two separate test vehicles operating respectively at Ka‐band (26.5‐31.5 GHz) and K‐band (20.0‐24.0 GHz). The realized Monolithic Microwave Integrated Circuits exhibit 18 dB gain for both versions, NF of 1.5 and 1.2 dB, respectively for the Ka‐band and K‐band version. Input and output matching are typically better than 12 and 15 dB.     

A W‐band RF‐MEMS switched LNA in a 70 nm mHEMT process

This work presents a monolithic integrated reconfigurable active circuit consisting of a W‐band RF micro‐electro‐mechanical‐systems (MEMS) Dicke switch network and a wideband low‐noise amplifier (LNA) realized in a 70 nm gallium arsenide (GaAs) metamorphic high electron mobility transistor process technology. The RF‐MEMS LNA has a measured gain of 10.2–15.6 dB and 1.3–8.2 dB at 79–96 GHz when the Dicke switch is switched ON and OFF, respectively. Compared with the three‐stage LNA used in this design the measured in‐band noise figure (NF) of MEMS switched LNA is minimum 1.6 dB higher. To the authors’ knowledge, the experimental results represent a first time demonstration of a W‐band MEMS switched LNA monolithic microwave integrated circuit (MMIC) in a GaAs foundry process with a minimum NF of 5 dB. The proposed novel integration of such MEMS switched MMICs can enable more cost‐effective ways to realize high‐performance single‐chip mm‐wave reconfigurable radiometer front‐ends for space and security applications, for example. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:639–646, 2015.     

Novel offset‐fed dual‐band aperture‐dipole composite antenna: Operating principle and design approach

Operating principle and design approach of a novel dual‐band aperture‐dipole composite antenna are proposed. It is shown that multiple operating modes can be simultaneously excited by employing offset‐feeding technique at first. After the behavior of each mode is studied, the operating principle of the antenna is analyzed and described. Then, an improved dual‐band aperture‐dipole composite antenna is formed and it is designed by using the proposed approach. The antenna is experimentally verified. It is demonstrated that two operating bands for radiation are ranged from 2.36 to 2.58 GHz and from 4.1 to 15.72 GHz, respectively, in which the reflection coefficient are both 相似文献   

A coplanar waveguide‐fed flexible antenna for ultra‐wideband applications

This paper presents a novel ultra‐wideband (UWB) antenna printed on a 70 μm thick flexible substrate. The proposed antenna consists of a hybrid‐shaped patch fed by coplanar waveguide (CPW). The ground planes on opposite sides of the feeding line have different height to improve antenna bandwidth. Simulation shows that the proposed antenna maintain wide bandwidth when changing its substrate's thickness and dielectric constant, as well as bending the antenna on a cylindrical foam. The proposed antenna is fabricated in laboratory with a simple and low‐cost wet printed circuit board (PCB) etching technique. Measured bandwidths cover 3.06 to 13.58, 2.8 to 13.55, and 3.1 to 12.8 GHz in cases of flat state and bent with radii of 20 and 10 mm, respectively. Measured radiation patterns show the antenna is omnidirectional in flat and bent cases.     

A planar ultra‐wide band asymmetric rat‐race hybrid coupler

In this article, an asymmetric ultra‐wideband rat‐race hybrid coupler with 180° phase shift is proposed. The primary goal of this work is to design a planar ultra‐wideband hybrid coupler with a microstrip structure by avoiding via holes and multi‐layer design. The bandwidth of an asymmetric ring hybrid is enhanced using shorted coupled lines, perturbation impedance techniques, and matching stubs. This hybrid coupler was designed and fabricated using Taconic TLX‐8 substrate with a thickness of 0.5 mm. The results of the simulation and measurement are promising and meet the desired specifications. This hybrid coupler yields a fractional bandwidth of 56% at the center frequency of 5.95 GHz based on ±1 amplitude imbalance between two output ports.     

Epsilon‐shaped circularly polarized strip and slot‐loaded ultra‐wideband antenna for Ku‐band and K‐band

A compact epsilon‐shaped (ε) ultra‐wideband (UWB) antenna for dual‐wideband circularly polarized (CP) applications has been investigated in this article. It consists of a stepped stub loaded modified annular ring‐shaped radiator and modified CPW ground plane. The ground plane is loaded with two semicircular notches and a spiral‐shaped slot. The impedance bandwidth (IBW) is 97.02% (10.4‐30 GHz) along with an overall footprint of 20 × 20 mm². The fractional axial ratio bandwidth (3‐dB ARBW) for two wide bands is 38.50% (13.30‐19.64 GHz) and 6.45% (26.25‐28.00 GHz), respectively. The proposed antenna is left‐hand circularly polarized with a peak gain of about 5.09 and 5.14 dB in both 3‐dB ARBW bands. The proposed antenna is dominating other reported CP antenna structures in terms of number of CP bands, 3‐dB ARBW, IBW, peak gain, and dimensions.     

Fork‐shaped patch printed ultra‐wideband slot antenna with dual band‐notched characteristics using metamaterial unit cells

In this article, a miniaturized fork‐shaped patch ultra‐wideband (UWB) planar wide‐slot antenna with dual band‐notched characteristics is proposed. With fork‐shaped patch, ultra‐wideband impedance matching from 3.1 to 13.2 GHz is easily achieved. Then, two novel and simple methods are applied to solve the difficulty for UWB slot antennas with fork‐shaped patch to realize band‐notched characteristics. By etching one pair of I‐shaped resonators on both branches of the fork‐shaped structure and adding a rectangular single split‐ring resonator in the rectangular openings of fork‐shaped patch, the wireless local area network (WLAN) band from 5.5 to 6.1 GHz and the International Telecommunication Union (ITU) 8 GHz band from 7.9 to 8.7 GHz are rejected, respectively. The coplanar waveguide‐fed UWB antenna is successfully designed, fabricated, and measured. The measured and simulated results show a good agreement. The antenna provides nearly stable radiation patterns, high gains and high radiation efficiency.     

Design and realization of an ultra‐low power sensing RF energy harvesting module with its RF and DC sub‐components

Herein, design, development, and analysis of ultra‐low power sensing energy harvesting modules and their subcomponents for ISM band applications have been studied with a holistic approach in an effort to achieve a feasible and high efficient RF energy harvesting performance. The complete harvester system designed and developed here consists of a zero‐bias RF energy rectifying antenna (rectenna), DC boost converters and energy storage super‐capacitors. Compared with the counterpart energy sources, the surrounding or transmitted wireless energy has low intensity which requires designs with high efficiency. To achieve a successful harvester performance, rectifier circuits with high sensitivity Schottky diodes and proper impedance matching circuits are designed. Dedicated RF signals at various levels from nanowatts to miliwatts are applied at the input of the rectenna and the measured input power versus the scavenged DC output voltage are tabulated. Furthermore, by connecting the rectifier to a high gain antenna and using a RF signal transmitter, the wireless RF power harvesting performance at 2.4 GHz was tested up to 5 m. The performance of the rectenna is analyzed for both low‐power detection and efficiencies. Impedance matching network is implemented to reduce the reflected input RF power, DC to DC converters are evaluated for their compatibility to the rectifiers, and super‐capacitor behaviors are investigated for their charging and storage capabilities. The measured results indicate that a wide operating power range with an ultra‐low power sensing and conversion performance have been achieved by optimizing the efficiency of the Schottky rectifier as low as ?50 dBm. The system can be used for battery free applications or expanding battery life for ultra‐low power electronics, such as; RFID, LoRa, Bluetooth, ZigBee, and low power remote sensor systems.     

A modified design approach for compact ultra‐wideband microstrip filters

A modified design approach for compact ultra‐wideband microstrip filters with cascaded/folded stepped‐impedance resonators is described. The key feature of the proposed method is to facilitate stronger coupling between stepped‐impedance resonators and, at the same time, eliminate the requirement of extremely small gaps in coupled‐line sections, as found in traditional designs. Simulations and measurements demonstrate that the filters designed with this technique exhibit good reflection, insertion‐loss, and group‐delay performance within the 3.1–10.6 GHz band. © 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE 2010.