Design of broadband single matching networks

In general commercially available software tools are preferred, to design broadband matching networks for wireless communication systems. But they need a properly selected matching network topology with good initial element values. Therefore, in this paper a new real frequency technique is presented, to generate broadband single matching networks with suitable initial element values. In the proposed method, load impedance is written in terms of ABCD-parameters of the desired matching network and the source resistor. Then, free parameters are optimized which in turn yields the desired matching network with initial element values. It is not needed to select a circuit topology for the matching network, which is the natural consequence of the matching processes. Also, there is no need to select the desired transducer power gain level; the proposed technique naturally provides a gain curve fluctuating around the final available level. Eventually, the initial design is improved by optimizing the performance of the matched system employing the commercially available computer-aided design (CAD) packages. An algorithm and two examples are given, to illustrate the utilization of the proposed technique.     

Design of practical broadband matching networks with commensurate transmission lines

To design broadband matching networks for microwave communication systems, commercially available computer aided design (CAD) tools are always preferred. But these tools need proper matching network topology and element values. Therefore, in this paper, a practical method is proposed to generate distributed-element matching networks with good initial element values. Then, the gain performance of the designed matching network can be optimized employing these tools. The utilization of the proposed method is illustrated by means of the given example. It is shown that proposed method provides very good initials for CAD tools.     

Design of Practical Matching Networks With Lumped Elements Via Modeling

It is a common practice to utilize commercially available software tools to design matching networks for wireless communication systems. Most of these tools require a properly selected matching network topology with good initial element values. Therefore, in this paper, a practical method is presented to generate matching networks with initial element values. In the implementation process of the proposed method first, the driving point immitance data for the matching network is obtained in a straight forward manner without optimization. Then, it is modeled as a realizable bounded-real input reflection coefficient which in turn yields the desired matching network with reasonable element values. Eventually, the initial design is improved by optimizing the performance of the matched system employing the commercially available computer-aided design (CAD) packages. An example is given to illustrate the utilization of the proposed method. It is shown that new method provides excellent results as a front-end when utilized together with CAD tools.     

A design method for lumped broadband MMIC matching networks withsemiuniform frequency-dependent losses

A design method for broadband MMIC matching networks which consist of lumped inductors and capacitors is presented. Based on a fictitious transformation between the lossy network and the lossless one, the transducer power gain (TPG) of the lossy network is calculated using impedance matrix and transmission parameter matrix methods. Then, on the basis of the result of TPG optimization, the matching network can be synthesized. Since only the complexity of the matching network needs to be specified, the advantage of the real frequency technique of B.S. Yarman and H.J. Carlin (1982) is retained. In this design procedure the frequency-dependent losses of lumped elements can be considered. Thus the actual gain response tends to coincide with the desired performance more than when the element losses are neglected. An example is given to show the application of the method to broadband GaAs FET amplifier design     

An Evolutionary Method for Synthesizing Low-Sensitivity Lossless Matching Networks

Whereas the present practice of designing matching networks for antennas is limited to conventional topologies, requiring a significant amount of domain knowledge, evolutionary algorithms can be used for automatically identifying unconventional designs that are more effective than would otherwise be developed. In this work, an automatic method to design lossless matching networks driven by an evolutionary algorithm (EA) that considers the sensitivities of the network parameters during the synthesis process is presented. To this end, 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. A 3D data structure based on the adjacency matrix is conveniently used to represent any type of network topologies. The proposed EA employs a novel set of topology variation operators, tailored for changing the circuit topology, and an association step, with the aim of reducing the number of nodes of the matching circuit. The efficiency of the proposed EA is tested in the synthesis of an impedance matching network for a VHF monopole whip antenna. This study’s results indicate a matching bandwidth improvement, a more uniformly distributed TPG along the operation frequency band and a more stable TPG regarding the components tolerance compared to the results obtained by previous approaches.     

A New Technique for Synthesis of Broad-Band Parametric Amplifiers

A new synthesis technique for providing precise design values for the realization of broad-band parametric amplifiers incorporating practical varactor diode models is presented. The method provides the designer considerable flexibility in choosing the topology of matching networks employed. An integral part of the synthesis scheme is the application of a least-squares optimization procedure which employs exact partial derivatives of the objective function. The partial derivatives are used in the optimization to compute the gain sensitivity of the amplifier with respect to all matching network and diode parameters. For the first time, sensitivity data is presented which quantitatively shows the effect of the device and matching network parameter variations on overall amplifier response. This permits the determination of critical parameters and provides a means for establishing tolerances for various circuit parameters. In comparison with conventional procedures, significantly improved broad-band designs are shown to result.     

微波集成公度线FET放大器的简化实频技术设计法

将简化实频技术发展用于具有公度线匹配网络的微波集成FET多级放大器的设计。勿需FFT的数学模型,勿需设定匹配网络的拓扑,按照通带内的噪声系数与传输增益指标要求可直接求得最佳的网络散射矩阵,据此即可综合公度线匹配网络。设计的实践证明此方法是适用于工程实际的。     

A tutorial on using genetic algorithms for the design of network topology

The design of network topology is an important part of network design, since network topology is directly associated with network operational behavior, capacity, reliability, and cost. This paper is a tutorial paper concerned with illustrating how the optimization capabilities of genetic algorithms can be used to design suitable network topologies considering basic topology problems. Simple genetic algorithms have been developed for the topology problem of mesh networks, considering single node and single link failure tolerance. The algorithms are based on criteria of two important measures: minimizing the length of communication links; and minimizing traffic flow through these links for given traffic loads. The first measure contributes to minimizing the cost of cabling, while the second measure contributes to minimizing the cost of link capacity. The work provides a useful approach and tools to network students and professionals concerned with the topology design of backbone networks. The developed software is made available on the Internet. Copyright © 2006 John Wiley & Sons, Ltd.     

基于遗传算法的宽带匹配网络的优化设计

本文采用遗传算法优化设计宽带匹配网络,通过适当的编码可同时对网络的拓扑结构和元件参数进行优化,并给出设计实例,通过与实频法相比较,表明遗传算法设计的匹配网络具有更优的匹配性能,说明遗传算法是一种设计匹配网络的有效方法。     

Computer design of linear frequency selective networks

An efficient algorithm is proposed for the computer synthesis of linear networks of arbitrary configuration. Given a circuit approximately realizing a network function T(s), the element values are perturbed until T(s) is precisely realized. In the process, positive elements may be "grown" across nodes as required, or may be forced to desired values. Examples in the areas of passive and active filter design are given, and limitations of the procedure are discussed. Also, the method is shown to be related to the theory of equivalent networks.     

Two-stage cut saturation algorithm for designing all-opticalnetworks

We design and optimize the physical topology of all-optical networks. This problem is more challenging than the traditional one for electronic communication networks, because of the wavelength-continuous constraint and it involves routing and wavelength assignment. In this problem, we are given the number of lightpaths required by every node pair and a cost specification, and our objective is to determine a physical topology of minimal cost. We formulate the problem, prove that it is NP-hard, and design an efficient algorithm called two-stage cut saturation algorithm for it. In the first stage, we relax the wavelength-continuous constraint and apply the main idea of the cut saturation method to determine a good initial network. In the second stage, we impose the wavelength-continuous constraint and perform routing and wavelength assignment to establish the specified lightpaths on the initial network. When some lightpaths cannot be established, we apply the main idea of the cut saturation method to optimize the insertion of additional links into the network. Simulation results show the following: (1) the proposed algorithm can efficiently design networks with low costs and high utilization and (2) if wavelength converters are available to support full wavelength conversion, the total cost of the links can be significantly reduced     

一种新型提高射频功率放大器PAE的电路技术

提出了一种新型提高射频功率放大器功率附加效率(PAE)的电路技术,该方法通过滤除二次谐波分量、反射叠加三次谐波分量以提高电路PAE,分析了相位匹配的机制及其影响因素.基于该技术设计了一款功率放大器,仿真结果表明:工作频率为918 MHz时,该功放的P1dB达到了30.05 dBm,功率附加效率达到了58.75%,较普通...     

Broadband impedance matching via lossless unsymmetrical lattice networks

In this paper, a broadband impedance matching network (equalizer) design algorithm has been proposed. In the equalizer, a lossless unsymmetrical lattice network has been utilized. The branch impedances of the lattice network are considered as singly terminated lossless LC networks, since it is not desired to dissipate power in the equalizer. After giving the algorithm, its usage has been illustrated via an example.     

A design technique for reliable networks under a nonuniform trafficdistribution

Many network-reliability analysis techniques define and compute a variety of reliability measures. Most techniques assume that network connectivity is the only determining factor in network reliability; and merely analyze an existing network structure but do not provide any methodology for reliable design. This paper presents a heuristic design algorithm to enhance the reliability of existing communication networks by modifying their topology. This algorithm improves the reliability of the least reliable node (reliability is the probability that messages transmitted from a given node reach their destination). To use this algorithm on large networks, a reliability analysis method is developed which determines approximate network reliability values in linear-time when an upper bound is placed upon the in-degree of all network nodes. The heuristic network design algorithm uses this approximate reliability analysis technique to place additional links. The goal of this link placement is to improve the reliability of the least-reliable node. The placement of additional links is a function of both the traffic distribution and the connectivity of the network. This process continues until either a desired level of network reliability is achieved or a maximum number of additional links has been added. A unique feature of this design strategy is that it has quadratic time-complexity when the maximum in-degree of all network nodes is limited     

Development of Integrated Broad-Band CMOS Low-Noise Amplifiers

This paper presents a systematic design methodology for broad-band CMOS low-noise amplifiers (LNAs). The feedback technique is proposed to attain a better design tradeoff between gain and noise. The network synthesis is adopted for the implementation of broad-band matching networks. The sloped interstage matching is used for gain compensation. A fully integrated ultra-wide-band 0.18-mum CMOS LNA is developed following the design methodology. The measured noise figure is lower than 3.8 dB from 3 to 7.5 GHz, resulting in the excellent average noise figure of 3.48 dB. Operated on a 1.8-V supply, the LNA delivers 19.1-dB power gain and dissipates 32 mW of power. The gain-bandwidth product of the UWB LNA reaches 358 GHz, the record number for the 0.18-m CMOS broad-band amplifiers. The total chip size of the CMOS UWB LNA is 1.37 times 1.19 mm².     

Concurrent design of Schottky diode limiter and LNA

In this paper concurrent design of Schottky diode based limiter and low noise amplifier (LNA), based on noise matching, is investigated to achieve minimum noise figure (NF) of the receiver chain. In design procedure of the LNA, the noise figure is minimum, gain at central frequency is 14.5 dB, and limiter structure tolerates up to 5 W continuous wave input power. In the proposed concurrent design, a pass-band filter is applied at the LNA output to attenuate undesired out-of-band signals. In the proposed design, the limiter-LNA is implemented with a 0.25 µm gate length AlGaAs/InGaAs pHEMT process. Measured noise figure of chain is 2.7 dB and average gain over 8.5–9.5 GHz frequency range and the gain at 9 GHz center frequency are 10 dB and 14.5 dB respectively. The performance results of proposed matching network are compared with traditional 50 Ω matching networks in limiter-LNA with identical circuit specifications.

     

On the design of broad-band loaded wire antennas using the simplified real frequency technique and a genetic algorithm

A novel design methodology for broad-band loaded wire antennas is presented that combines the genetic algorithm and the simplified real frequency technique (SRFT) to remove the requirement of choosing the types of load circuits and matching networks a priori. Analytical expressions for the impedance functions of load circuits and matching networks are obtained in the form of rational polynomials via the SRFT. The location of loads on the antenna and the resistance functions of the load circuits and matching networks are optimized using a genetic algorithm. Maximization of system gain in the azimuth and minimization of voltage standing wave ratio are sought as design objectives. The circuit topologies and the component values are automatically arrived at using Darlington synthesis after the optimization process is complete. Also demonstrated, is the use of this procedure to achieve broad-band operation in the HF band for the unloaded and loaded monopoles assuming electronically switched matching networks.     

Synthesis method based on genetic algorithm for designing EDFA gain flattening LPFGs having phase-shifted effect

We propose a new synthesis method based on the genetic algorithm for the design of erbium-doped fiber amplifier gain flattening filters. Our genetic algorithm iterates starting with the long period fiber gratings structure constructed by inserting the phase-shifted long period fiber gratings in the middle of the structure, for the more accurately matched spectrum to the desired erbium-doped fiber amplifier gain flattening filter. To verify a synthesizing technique using the proposed algorithm, we have synthesized the long period fiber gratings structures according to the inverted gain spectrum of a commercially available erbium-doped fiber amplifier over the entire 1525–1570 nm range, theoretically. We have also obtained the synthesized structure was more accurate than the structure without phase-shifted section.     

Selectivity enhancement of certain low-sensitivity RC active networks †

A technique is described for improving the selectivity of a low-sensitivity multi-loop negative feedback active network, which uses one operational amplifier. Voltage amplifiers with positive finite gain are introduced inside the various loops of the network. This simplifies quite considerably the network function and improves the selectivity for a given range of element values while not affecting the low sensitivity of the network. Also, additional low impedance outputs are available which for a particular input make the network suitable for the simultaneous realization of more than one function (with common poles but different zeros). Second and third-order networks are examined in detail and experimental results arc given from their use in the realization of a band-pass and a low-pass filter.