Improving conflicting specifications of time‐modulated antenna arrays by using a multiobjective evolutionary algorithm

By using the time modulation technique in antenna arrays, the stringent requirements on excitation error tolerance can be relaxed. However, the sideband signals spaced at multiples of the modulation frequency need to be suppressed in some applications. Multiobjective optimization is an important tool in the design of arrays with conflicting goals, such as low sidelobe level, low sideband level, and narrow beamwidth in the time‐modulated antenna arrays. In this paper, a novel multiobjective evolutionary algorithm based on objective decomposition (MOEA/D) with differential evolution operator and objective normalization technique is employed for the time‐modulated array synthesis, which is typically a problem with disparately scaled conflicting objectives. The effectiveness of the method is demonstrated by comparing the performances obtained by MOEA/D with those of previously reported results obtained by a single‐objective differential evolution algorithm and simulated annealing technique. Copyright © 2011 John Wiley & Sons, Ltd.     

Smith圆图辅助设计低噪声宽频带放大器

接收微弱射频信号需要研究低噪声放大器的设计,文中在分析传统低噪声放大器设计的基础上引入对放大器匹配电路品质因数,扩宽放大器的频带;通过加入电流负反馈及在负载端并联电阻,提高放大器的稳定性、降低放大器驻波比,得到宽频带低噪声放大器的设计方法.仿真结果表明设计的放大器工作绝对稳定.     

可调窄带滤波器中低噪声放大器的优化设计

低噪声放大器(简称低噪放)是射频接收前端中的重要部件。设计性能优良的低噪声放大器能够极大的提高通信系统接收机灵敏度和通信质量。本文对微波放大电路的设计方法进行了探讨,并在ADS软件界面上进行了微波窄带滤波器低噪声放大器的优化设计。     

Base coupled differential amplifier: a new topology for RF integrated LNA

A new topology of bipolar low noise amplifier (LNA) for RF applications, named base coupled differential (BCD), is presented. The proposed approach is compared by simulation against most classical topologies. The BCD configuration has the key advantage to join an integrated matching on a single‐ended input with a differential output. This is done by using down‐bond wiring, so that no integrated inductors are needed. The main advantages of this new topology are a drastic area reduction and an increased linearity range (or a reduced biasing current with the same linearity) together with a noise figure (NF) and voltage supply reduction. Particularly, the BCD LNA presented in this paper has been designed for 2.44GHz frequency operation. It is characterized by a NF of 1.93dB, a voltage gain (Av) of 19.5dB, an input impedance of 50Ωa third Input‐referred Intercept Point (IIP3) of ‐7.25dBm and a dissipated power (PD) equal to 19mW. Copyright © 2003 John Wiley & Sons, Ltd.     

Figures‐of‐merit genetic extraction for InGaAs lasers,SiGe low‐noise amplifiers,and ZnSe/Ge/GaAs HBTs

In this paper, we have successfully developed an intellectual parameter‐extraction methodology on the basis of a genetic algorithm (GA), involving the efficient search‐space separation and local‐minima‐convergence prevention schemes. Via an evolutionary simulation tool complemented with appropriate analytic equations, the enhanced approach has been applied to determine the significant figures‐of‐merit (FoMs), including internal quantum efficiency (η_i) as well as transparency current density (J_tr) of semiconductor lasers, minimum noise figure (NF_min) as well as associated available gain (G_A,assoc) of low‐noise amplifiers (LNAs), and DC as well as AC characteristics of heterojunction bipolar transistors (HBTs). For the first time, demonstrated FoM‐extraction results, which coincide well with the actually measured data, for state‐of‐the‐art InGaAs quantum‐well lasers, advanced SiGe LNAs, and abrupt ZnSe/Ge/GaAs HBTs are simultaneously presented to validate this multi‐parameter analysis and robust optimization. Copyright © 2011 John Wiley & Sons, Ltd.     

A simple and efficient honey bee mating optimization approach to performance characterization of a microwave transistor for the maximum power delivery and required noise

In this work, a simple, efficient and multi objective Honey Bee Mating Optimization (HBMO) is presented for the performance characterization of a microwave transistor to deliver maximum power to the load with the required noise F_req. Thus all the possible compatible {F_req ≥ F_min, V_out = 1, G_Tmax} triplets and the corresponding source Z_S and load Z_L = Z^*_out (Z_S) terminations can be obtained in the device operation domain of (V_DS, I_DS and f) without working analytically for the nonlinear performance and stability equations. HBMO is a recently emerging meta‐heuristic algorithm that combines the powers of the simulated annealing and genetic algorithms. Here, a microwave transistor is chosen as a case study, effectiveness and efficiency of the HBMO are shown by comparing its performance to those of the standard meta‐heuristics Genetic and Particle Swarm algorithms and the mean cost results for 10 runs are found to be 0.22, 1.65 and 1.85, respectively, for the comparable execution times. Furthermore, all the numerical results are found to agree with their analytical counterparts obtained using the microwave, linear circuit and noise theories. The Feasible Design Target Space FDTS can be built by the cross relations among all the possible compatible {F_req ≥ F_min, V_out = 1, G_Tmax} triplets together their terminations {Z_S, Z_L = Z^*_out (Z_S)} covering all the possible amplifier designs where both noise figure and output power are at a premium. Copyright © 2015 John Wiley & Sons, Ltd.     

Improved differential evolutionary algorithm for nonlinear identification of a novel vibration‐assisted swing cutting system

Vibration‐assisted swing cutting (VASC) is a new precision machining technology. VASC not only inherits the characteristics of EVC intermittent cutting but also alleviates the problem of EVC residual height. However, system identification is key if you want to achieve precise control. In order to solve this problem, a new improved differential evolutionary (IDE) algorithm is proposed to identify and optimize the Hammerstein‐Wiener model parameter in VASC system. IDE algorithm is applied to transform the identification problem of the model into the optimization problem in the parameter space, and the optimal solution of the parameter of the model in the parameter space is obtained. Meanwhile, the IDE algorithm and the conventional five differential evolutionary algorithms perform performance comparison tests on six different test functions. The test results show that the IDE algorithm is strengthening the global search capability, accelerate the convergence rate to the global optimal solution, and indicate that the IDE algorithm can be effectively applied to the parameter optimization of Hammerstein‐winner model. Based on the input and output data collected from the experiment, the accuracy of the identification model can be up to 98%, which prove the superiority of the proposed IDE algorithm for system identification.     

应用自适应微分进化算法的配电网综合优化

单方面的网络重构或无功优化均不能实现最大程度的配电网优化,因此需要将两者综合考虑,为此提出了基于微分进化算法的配电网综合优化算法。为与无功优化的整数编码方式统一,网络重构采用编码长度最低的环路支路整数编码方式,以将网络重构和无功优化同时引入进化过程。同时将自适应变异及进化参数调整策略引入进化过程,以在确保获得最优解的同...