Broadband Matching Networks Research Articles

Four-Arm Spiral Antenna Fed by Tapered Transmission Line

This letter presents a four-arm Archimedean spiral antenna with a novel integrated tapered transmission line feed structure. The center-fed spiral antenna consists of a radiation region with an Archimedean spiral configuration and a transmission region that comprises four spiral-shaped transmission lines with exponentially decreasing widths. The tapered transmission line, acting as an impedance transformer, provides a broadband matching network between the 50-Ω input impedance and the higher impedance of the radiation region. Using this design, a mode-1 spiral antenna attains a return loss of greater than 15 dB and a 3-dB broadside axial ratio throughout the 0.8–3-GHz band. The fabricated antenna demonstrates good agreement between the simulated and measured results.

Reflection Modeling Based Broadband Matching Network Design

Abstract In this paper, a new broadband matching network design approach based on reflection modeling is proposed, which has two parts: impedance data generation and modeling. In the approach, firstly the output impedance data of the matching network is obtained to get the desired flat transducer power gain in the passband. Next the output reflection data are calculated using the obtained impedance data, then they are modeled as a bounded real function. Then this function is synthesized and the desired lossless matching network with initial element values is obtained. A double matching example is solved to illustrate the use of the proposed approach. It is seen that proposed approach provides suitable initials for CAD tools for final trimming.

Design of continuous‐mode GaN power amplifier with compact fundamental impedance solutions on package plane

A novel methodology for designing broadband Class-J power amplifiers (PAs) with compact fundamental impedances on the package plane is presented. A simple transistor model with knee voltage region is built to predict efficiency performance and clipping waveforms caused by the clipping effects. To realise the proposed impedance solutions, a broadband matching network is presented based on the shot-stepped Chebyshev impedance transformer. A broadband Gallium Nitride (GaN) PA is designed using this method and achieve a very wide operation band from 0.8 to 3.6 GHz. More than 10 dB gain, 55.8-74.1% drain efficiency and around -30 dBc adjacent channel power ratio are measured without linearisation throughout the entire band. At 33 dBm average output power level, an average power-added efficiency of 27% and adjacent power leakage ratio of -46.3 dBc is obtained with 9 dB peak-to-average power ratio 20 MHz long-term evolution test signals at 2.4 GHz.

Synthesis of Low Sensitivity Broadband Matching Networks Using Clonal Selection Algorithm

This paper presents a new methodology for synthesis of broadband matching networks based on Clonal Selection Algorithms (CSA). This metaheuristic uses the hypermutation as only variation operator resulting in a gradual evolving of the network topology. A closed form expression for the transducer power gain (TPG) sensitivity with respect to the component values is employed, in such a way that the effects of the components tolerance on the matching network performance can easily be quantified. The evolvable function proposed is single-objective and eliminates the difficult task of assigning appropriate weights to parameters. The evaluation of the TPG sensitivity enables the designer to identify and remove irrelevant components of the circuit, simplifying it. The efficiency of the methodology is tested in two cases found in the literature: the traditional project of impedance matching for a simple RLC load proposed by Fano [1]; and a real synthesis of impedance matching network for a monopole whip antenna, proposed in [2]. The results are compared with other existing methods.

Broadband matching via reflection function optimization

SummaryIn this paper, a practical approach is presented for designing broadband matching networks via reflection function optimization. In the proposed algorithm, the input or output reflection function of the matching network is expressed in terms of three real polynomials describing the matching network, load and generator reflection coefficients. Next one of the polynomials is optimized to get minimum reflection function values in the passband. Then matching network topology and element values are obtained via the formed input reflection coefficient expression. Two examples are presented to explain the usage of the new approach. Copyright © 2016 John Wiley & Sons, Ltd.

Setting Parameters Influence on Accuracy and Stability of Near-Field Scanning Microwave Microscopy Platform

In this paper, the impact of different setting parameters on the performance of a microwave microscope is evaluated. This study is performed on a homemade near-field scanning microwave microscope built up with a conventional vector network analyzer and a vertical coaxial evanescent probe. A broadband matching network based on an interferometric technique is inserted between the analyzer and the probe to enhance the measurement sensitivity/accuracy in the frequency range 2–20 GHz. The performance of the system in terms of measurement accuracy and stability is derived as a function of different setting parameters. Microwave surface imaging of subwavelength features is evaluated as a demonstration. This paper provides a guide for best practice in microwave microscopy.

Polarization Reconfigurable Broadband Rectenna With Tunable Matching Network for Microwave Power Transmission

A broadband polarization reconfigurable rectenna is proposed, which can operate in three polarization modes. The receiving antenna of the rectenna is a polarization reconfigurable planar monopole antenna. By installing switches on the feeding network, the antenna can switch to receive electromagnetic (EM) waves with different polarizations, including linear polarization (LP), right-hand and left-hand circular polarizations (RHCP/LHCP). To achieve stable conversion efficiency of the rectenna ( $\eta_{r}$ ) in all the modes within a wide frequency band, a tunable matching network is inserted between the rectifying circuit and the antenna. The measured $\eta_{r}$ changes from 23.8% to 31.9% in the LP mode within 5.1–5.8 GHz and from 22.7% to 24.5% in the CP modes over 5.8–6 GHz. Compared to rectennas with conventional broadband matching network, the proposed rectenna exhibits more stable conversion efficiency.

A 1.8-2.8 GHZ HIGHLY LINEAR BROADBAND POWER AMPLIFIER FOR LTE-A APPLICATION

This paper proposes a fully integrated broadband power amplifier for LTE-A application using GaAs HBT process. To improve the linearity and broadband performance, RC feedback structures and dynamic bias circuits are employed and designed through optimization. With careful design of the broadband matching networks in the proposed 3-stage power amplifier topology, a power gain above 21.6 dB is achieved from 1.8 GHz to 2.8 GHz. Driven by an 80 MHz wideband LTE-A signal with PAPR of 7.5 dB, the designed RF power amplifier achieves an average output power about 22 dBm at ACLR = −30 dBc over the entire 1 GHz frequency band. Considering the broad bandwidth of the driven signal and wide frequency coverage bandwidth, the performance merits of the proposed design compare favorably with the state-of-the-art.

An 85-W Multi-Octave Push–Pull GaN HEMT Power Amplifier for High-Efficiency Communication Applications at Microwave Frequencies

This paper proposes a design methodology for multi-octave planar push–pull power amplifiers (PPPAs) to tackle the challenges associated with the integration of planar balanced to unbalanced transformers (baluns) with packaged transistors characterized by significant parasitics. This methodology relies on carefully selecting the balun’s placement and adding external matching networks to separately control the odd- and even-mode impedances presented to the power amplifier (PA) to ensure high-efficiency operation over a broad range of frequencies. Proper second harmonic impedances are obtained by placing the balun in close proximity to the transistors’ terminals and repurposing the packaged transistors’ leads into a coupled-line with a high coupling coefficient. Furthermore, adequate odd-mode terminations are realized using broadband matching networks at the unbalanced side of the baluns. Following this methodology, an 85-W PPPA was designed using off-the-shelf packaged gallium–nitride high electron-mobility transistors. The fabricated PA demonstrated drain efficiency and output power above 45% and 46.5 dBm, respectively, over the frequency band spanning from 0.45 to 1.95 GHz. Furthermore, the fabricated PA was successfully linearized using digital predistortion when driven with single- and multi-band modulated signals. Overall, the fabricated PA had the best reported power, efficiency, bandwidth, and second harmonic rejection combination for a multi-octave PPPA designed with input and output baluns using packaged off-the-shelf transistors.

0.4–3.0 GHz highly efficient harmonic‐tuned power amplifier

An optimisation-based method is proposed for the design of highly efficient harmonic tuned-power amplifier (HT-PA) with multi-octave bandwidth. The distributed basic matching cell with L-type structure is utilised to construct the broadband matching network, whose topology and parameters are determined through optimisation. To validate the proposed method, a 0.4–3.0 GHz HT-PA is implemented and the power added efficiency of 53–72%, output power of more than 40 dBm and 10–12 dB gain are achieved across the frequency band. When tested with 20 MHz long-term-evolution advanced signals, the broadband HT-PA shows about –30 dBc adjacent channel leakage ratio at about 36 dBm average output power, with drain efficiency higher than 36%.

Millimeter-Wave Low-Noise Amplifier Design in 28-nm Low-Power Digital CMOS

This paper presents the design of a 60-GHz low-noise amplifier (LNA) in a 28-nm low-power (LP) bulk CMOS process. As the technology is optimized for digital LP applications, the design of millimeter-wave (mm-wave) circuits requires high-frequency design and modeling of all active and passive devices. This includes the development of a suitable RF-transistor layout, as well as transmission lines and high- $Q$ capacitors. The mm-wave circuit design aspects are further discussed with considerations about possible dc-distribution approaches, broadband matching networks, and optimum transistor loads. The proposed approach and device models have been validated with the fabrication and characterization of a two-stage 60-GHz LNA. This circuit exhibits 13.8 dB of power gain, 18 GHz of bandwidth, 4 dB of minimum noise figure, and an input referred 1-dB compression point at $-$ 12.5 dBm consuming 24 mW of dc power. Based on this performance and to the authors’ best knowledge, the presented amplifier shows the highest reported value for a commonly used figure-of-merit of 60-GHz LNAs.

Design of dual‐band gan doherty power amplifier using a simplified structure

ABSTRACTIn this article, we present a simplified Doherty power amplifier (DPA) architecture for the easy implementation of dual‐band operation. The proposed DPA structure eliminates the 35 Ω quarter wavelength impedance inverters used in the conventional DPAs by matching the output impedances of the carrier and peak amplifiers of the DPA to other values (e.g., 100 Ω). The electrical lengths of the offset line and the phase compensation line are carefully chosen to enhance the Doherty effect (high efficiency at back‐off power level) at two assigned frequency bands. Broadband matching networks are also designed to increase the operation bandwidths at the two designed bands. To prove the design concept, a dual‐band DPA is designed and measured. In the first frequency band (550–650 MHz), the designed DPA provides 60.6–76.3% drain efficiency (DE) at full output power, 46–54.9% DE at 6 dB of output power back‐off (OBO); in the second frequency band (950–1050 MHz), the designed DPA provides 51.4–61.2% DE at full output power, 35–38% DE at 6 dB of OBO. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:953–956, 2015

Broadband high‐efficiency power amplifier with harmonic suppression based on load‐pull technique

ABSTRACTIn this letter, a novel design method for broadband and efficient power amplifier (PA) is proposed and a broadband PA with a compact matching topology is designed and fabricated to verify the validity of the method. In the method, specific attention has been paid to harmonic suppression to enhance efficiency and an appropriate design space of the fundamental and harmonic impedances, based on load‐pull technique which actually takes into account of the influences of the parasitics, is found to alleviate the difficulty of designing broadband matching network. Then a compact matching network topology is proposed to lead the fundamental and second harmonic impedances to the design space on the Smith chart over a wide bandwidth, simultaneously. The fabricated PA exhibits greater than 63% power added efficiency from 1.5 to 2.5 GHz (50% relative bandwidth), and 40.5–42 dBm saturated output powers. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:481–485, 2015

Design of Practical Broadband Matching Networks With Mixed Lumped and Distributed Elements

Computer-aided design (CAD) tools are always preferred for designing broadband matching networks. However, these tools give excellent results when the suitable matching network topology and initial element values are provided. Therefore, in this brief, a new initialization algorithm is proposed to get suitable network topology and element values for CAD tools. Then, the power transfer capability of the matching network can be improved by using any CAD tool. It is clear from the example studied that the new method generates excellent initials.

Synthesis of matching networks for microwave active circuits based on genetic algorithm

ABSTRACTA new genetic algorithm‐based technique for the synthesis of broadband matching and compensation networks used in microwave active circuits is presented. It allows the complete control over network configurations and element values leading to convenient practical solutions. The technique is implemented in the software tool GENESYN. As an example, the design of interstage network that compensates the transistors' gain slope and simultaneously provides DC bias in 4–6 GHz two‐stage FET amplifier is demonstrated. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2719–2722, 2014

High Precision Synthesis of a Richards Immittance Via Parametric Approach

A Richards immitance is a positive real function expressed in terms of the Richards variable λ = tanh(pτ) = Σ+jΩ where p=σ+jω is the classical complex frequency. A Richards immittance can be synthesized as a lossless two port terminated in a resistance as in Darlington's synthesis such that the two-port consists of commensurate transmission lines. In this paper, a high precision method is presented to synthesize a Richards immittance as a lossless two-port constructed with cascade connections of equal length transmission lines, as well as short and open stubs. The new method of synthesis utilizes Bode procedure (or Parametric Method) to correct an immitance function specified in the complex Richards variable λ at each step of the synthesis. It is verified that new technique can synthesize a randomly generated Richards immitance function yielding 25 commensurate lines with the accumulated numerical error less than 10-3. A complete synthesis package is developed in MatLab and successfully integrated with the Real Frequency Technique to design broadband matching networks. Examples are presented to show the merits of the new Richards synthesis tool.

Design of GaN Doherty Power Amplifiers for Broadband Applications

This letter presents a modified Doherty power amplifier (DPA) architecture to release bandwidth limitation of the conventional DPA. The proposed DPA structure eliminates two quarter wavelength impedance inverters used in the conventional DPAs. Instead, both the carrier and peak amplifiers in the proposed DPA are matched to 70 Ω at the output ports, which enables an easier implementation of broadband matching networks. Broadband input matching network (IMN) and output matching network (OMN) are then designed to achieve wideband DPA with enhanced performance. To verify the design concept, a broadband DPA is designed, fabricated, and measured on a RT/Duroid 5880 substrate with 2.2 dielectric constant and 0.787 mm substrate thickness. In the working frequency bands (0.8 to 1.2 GHz), the designed DPA provides 50.8% to 78.5% power-added efficiency (PAE) at full output power, 30.3% to 40.1% PAE at 6 dB of output power back-off (OBO), 10.8 to 14.8 dB gain (the gain variation is within 2.6 dB over different input power levels at each specific frequency), and maximum output power between 40.2 and 42.9 dBm.

Broadband Predistortion Circuit Using Zero Bias Diodes for Radio Over Fiber Systems

A low-cost broadband analog predistortion circuit (PDC) is designed and experimentally verified in a radio over fiber (RoF) system. A miniature hybrid microwave integrated circuit technique is used to reduce the size and parasitics of PDC. Only two zero bias GaAs beam lead detector diodes and capacitors are used in the PDC. The diodes can be biased at due to zero bias characteristic so that power consumption is reduced. No broadband matching network is required because of high series resistance of the zero bias diodes. The linearization performance is evaluated using an RoF system without and with the PDC. It is shown that the PDC improves the input 1-dB compression power by 0.4-2.2 dB from 7 to 18 GHz; and spurious free dynamic ranges are improved by ~ 10 dB from 7 to 14 GHz and ~ 6 dB from 15 to 18 GHz, limited by fifth order nonlinear distortion.

Design of Practical Broadband Matching Networks With Lumped Elements

It is always preferable to use commercially available software tools to design broadband matching networks for microwave communication systems. However, for these tools, the matching network topology and element values must be selected properly. Therefore, in this paper, a practical method is presented to generate matching networks with good initial element values. Eventually, the performance of the designed matching network is optimized by employing the commercially available computer-aided design (CAD) tools. An example is given to illustrate the utilization of the proposed method. It is shown that the proposed method provides very good initials for CAD tools.

Multiband and Small Coplanar Antenna System for Wireless Handheld Devices

Multiband and small antennas are strongly demanded in current wireless handheld or portable devices that require multiband operation. Nowadays, trends are focused on exciting ground plane radiation modes in order to reduce as much as possible the volume devoted to the antenna element. This paper studies different geometries for determining which one better excites a ground plane radiation mode at different frequency regions. The results demonstrate that a non-resonant pad element attains the best tradeoff between performance and geometry complexity. A multiband antenna system featuring small coplanar pad elements is proposed for providing operation at the communication standards LTE700 (698-787 MHz), GSM850 (824-894 MHz), GSM900 (880-960 MHz), GSM1800 (1710-1880 MHz), GSM1900 (1850-1990 MHz), UMTS (1920-2170 MHz), LTE2100 (1920-2170 MHz), LTE2300 (2300-2400 MHz), LTE2500 (2500-2690 MHz) as well as at the satellite positioning systems GPS (1575 MHz), Galileo L1 (1559-1591 MHz), Glonass (1592-1609 MHz). A radiofrequency system comprising broadband matching networks is included to provide the required impedance bandwidth. Numerical results give physical insight into the behavior of the proposed planar element. A prototype is built to demonstrate the feasibility of the proposal. The proposed radiating system is appealing for the new wireless handheld devices due to its small size (153 ), planar profile, and multiband performance.