Nonlinear modeling of class‐E microwave power amplifiers

Verification of the Materka–Kacprzak model suitable for highly saturated MESFET operation is presented. To examine the validity of the model, a broadband microwave class‐E power amplifier was designed and fabricated using a Siemens CLY5 MESFET transistor. A 200 MHz bandwidth (22%) from 0.82 to 1.02 GHz with a power‐added efficiency greater than 60% was measured at an input power level of 15 dBm with a constant output power of 24 dBm. ©1999 John Wiley & Sons, Inc. Int J RF and Microwave CAE 9: 93–103, 1999     

Multiharmonic manipulation for highly efficient microwave power amplifiers

Multiharmonic manipulation is presented as the most effective solution to improve power amplifier (PA) efficiency performances. Remarkable improvements in output power, power gain and power‐added efficiency (PAE) are demonstrated, properly manipulating the input and output second and third harmonics, as compared to more classical design approaches. Experimental results at 5GHz confirm the feasibility, the validity and effectiveness of the proposed approach, increasing the maximum measured power‐added efficiency from 39% to 61% © 2001 John Wiley & Sons, Inc. Int J RF and Microwave CAE 11: 366–384, 2001     

Switched-mode RF and microwave parallel-circuit Class E power amplifiers

The parallel-circuit Class E tuned power amplifiers with load networks consisting of either one capacitance and one inductor or a parallel LC circuit and series filter are described and analyzed. The elements of the load networks are defined using the same analytical approach with a set of the exact design equations. The ideal collector voltage and current waveforms for both configurations demonstrate a possible 100% efficiency and do not overlap. RF and microwave applications are demonstrated based on the simulation and experimental results of low-voltage InGaP/GaAs HBT and high-voltage LDMOSFET power amplifiers. These switched-mode parallel-circuit Class E power amplifiers offer a new challenge for RF and microwave power amplification by providing high-efficiency operating conditions. © 2003 Wiley Periodicals, Inc. Int J RF and Microwave CAE 14, 21–35, 2004.     

A design method for highly efficient power amplifiers: Application to class F amplifiers

A method for the design of high-power-added efficiency amplifiers, based on optimum load investigations, is presented. The key point of the proposed method is the successive adjustments of the device loads presented at fundamental and harmonic frequencies. Effects of harmonic tuning on power performances are investigated by an extensive analysis of current and voltage drain waveforms. Experimental results of two microwave amplifiers at 1.75 GHz and 7.5 GHz, clearly show the value of this method. Their designs and performances are reported. © 1996 John Wiley & Sons, Inc.     

Itrative design-oriented analysis method for class-ab high-efficiency microwave power amplifiers

Optimum choice of bias point, load and drive level for solid-state power amplifiers is performed via a design methodology based on a novel iterative analysis method. The effectiveness of the proposed methodology and the corresponding level of accuracy is demonstrated through a comparison with the results of a more elaborate commercial CAD software and with experimental data, © 1994 John Wiley & Sons, Inc.     

Nonlinear excitation controller design for power systems： an I＆I approach

The Immersion and Invariance(I&I) methodology provides a novel approach for nonlinear system control, which is distinct from the traditional feedback linearization and backstepping method.In this paper,a new excitation controller is designed for single machine infinite bus system(SMIBS) based on the I&I approach.Firstly the dynamic model of SMIBS is homeomorphously transformed to a specific form for which a stable lower-order target system is selected.Then the I&I excitation controller is designed by immersing the transformed system into the target system.Simulation results from PSCAD/EMTDC demonstrate that the proposed controller guarantees transient stability of the system after large disturbances.     

S波段E类功率放大器的设计

开关模式E类功率放大器的理论效率可达100%,可用于天气雷达发射机系统中。采用GaN HEMT器件,设计了一个在2.8 GHz频点下的E类功率放大器,输出功率达到40 dBm,PAE为67%,增益为13 dB。此外,设计的微带负载网络对谐波进行了有效抑制。     

Nonlinear control design for excitation controller and power system stabilizer

The paper focuses on the design of excitation controller and power system stabilizer (PSS) control schemes to enhance voltage regulation and transient stability. To design the excitation controller, the nonlinear models of the synchronous generator and electrical system are suitably arranged to give an input-output nonlinear model, which is subsequently made linear by a compensating law. The PSS control scheme is designed according to a new approach, based on the inverse system theory, which guarantees satisfactory swing damping by reducing the mutual influence between transient stability and voltage regulation. The results obtained by numerical simulations in different operating conditions confirm the effectiveness of the proposed design, also in the presence of model parameter inaccuracy.     

Large‐signal variability of microwave power amplifiers through efficient device sensitivity‐based physical modeling

In the present article they present a comprehensive variability analysis of microwave power amplifiers in various operating classes by means of a recently developed numerically efficient technique for the physics‐based variability analysis of devices operated in nonlinear conditions. Both a class A and a deep class AB power amplifier are considered, with the active device undergoing variations of main physical parameters such as doping, gate work function, and gate length. The results presented show for the first time that the physics‐based variability analysis of nonlinear circuits is feasible and allows for a direct link between the PA performance uncertainty and the active device technological parameter variations. Both deterministic and statistical variations are taken into account, showing that the approach of Donati Guerrieri et al. (2016) allows for an aggressive reduction in computation time with respect to the variability analysis by means of conventional approaches, while retaining very good accuracy for parameter variations up to 10% of their nominal value. The highest sensitivity of the class A stage is found for the drain efficiency, while the class AB stage has a more involved behavior, with the highest sensitivity shifting from the drain efficiency to the output power as the input power increases.     

A method for stability analysis of small-signal microwave amplifiers

This paper presents a method for analyzing the stability of small-signal microwave amplifiers with any topology. This analysis is performed using the Nyquist criterion and allows detection of the so-called odd-mode instabilities. The method is easily applicable by using commercially available microwave CAD. © 1998 John Wiley & Sons, Inc. Int J RF and Microwave CAE 8: 293–302, 1998.     

Efficient numerical CAD technique for RF and microwave amplifiers

The real frequency technique (RFT) is an efficient numerical method to design the matching networks of microwave active circuits. It provides several advantages over most of the usual techniques. By directly including measured scattering and noise parameter data, it does not require any rational functions or circuit models. Moreover, a predetermined matching circuit topology is not necessary. The described method also allows the design of stability-guaranteed broadband circuits when employing potentially unstable transistors. With the Levenberg–Merquardt algorithm, the RFT can be applied to simultaneously optimize transducer power gain, input and output VSWRs, noise figure, and group delay of a multistage microwave active circuit. Applications as different as low-noise amplifier, active filter, or broadband amplifier are possible. © 1998 John Wiley & Sons, Inc. Int J RF and Microwave CAE 8: 131–141, 1998.     

TD-SCDMA射频功率放大器研究

对采用时分双工模式的TD-SCDMA移动通信系统中的射频功率放大器的EVM性能进行了分析。通过分析功率放大器瞬态响应,得到射频功率放大器在时分双工模式下的EVM指标比频分双工模式下的EVM指标有所恶化的原因,并对基于MW6IC2240的射频功率放大器电路建立了一个二阶R-C模型,进一步分析了功率放大器件和外围电路的参数对功率放大器瞬态响应的影响,得到功率放大器瞬态响应的开关上升时间大小会影响时分双工模式下射频功率放大器EVM性能。基于此,提出了改进TD-SCDMA系统中射频功率放大器EVM性能的方法。改进后的TD-SCDMA射频功率放大器在时分双工模式下的EVM性能与频分双工模式时接近。     

Process and terminations variations aware stability criteria for microwave amplifiers

Two novel process variations aware, necessary and sufficient conditions suitable for implementation in CAD optimizers are proposed to check amplifiers stability. Case studies are presented, showing that the new criteria allow robust amplifier design, under variation of active device immittance parameters in pre‐specified rectangular regions, due to manufacturing tolerances. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE 23: 619–626, 2013.     

An eclectic approach to design tunable amplifiers

Broadband amplifiers that can accommodate commercial communication standards such as GSM, UMTS, Wi‐Fi, and Wi‐Max are extremely important for radio equipment manufacturers. To achieve this coverage, the amplifier should provide high gain and efficiency over a band from 800 to 5200 MHz. Although there are transistor devices that have cut‐off frequencies well over these frequencies, amplifiers covering such a broad‐bandwidth are difficult to design due to the requirement of broadband matching networks. In this work, design of broadband tunable matching networks is investigated using Real Frequency Direct Computational Technique (RF‐DCT). In order to be able to work on sample structures, impedance transforming filters are chosen and a broadband tunable matching network has been designed. Implementation of tunable inductors is investigated and the performance of a tunable matching network using tunable inductors and capacitors is demonstrated. Eventually a broadband frequency tunable amplifier has been designed using the tunable inductor concept. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013.     

Nonlinear decentralized controller design for multimachine power systems using Hamiltonian function method

In this paper, we first express a multimachine power system as a Hamiltonian control system with dissipation. Then, using the Hamiltonian function method a decentralized excitation control scheme, as a static measurable feedback, is proposed to stabilize the multimachine power system. Then, it is shown that the control scheme with properly chosen parameters is also an H_∞ control, which solves the problem of disturbance attenuation simultaneously. Finally, the design technique is demonstrated by a three-machine power system.     

Behavioral modeling of power amplifiers for wireless applications

In this paper, an improved empirical behavioral model for radio‐frequency power amplifiers (RF‐PAs) is presented. The model was implemented in a commercial nonlinear microwave simulator. It belongs to the category of bandpass PA models, which exhibits memory effects due to the low frequency dependence of bias and temperature. Additionally, it facilitates accurate and efficient system level simulations of RF‐PA large‐signal behaviors such as self‐bias, AM‐AM, AM‐PM, gain expansion effects, and intermodulation distortion (IMD) sweet‐spots. The model was validated using measurement data obtained from a commercial CDMA PA at 1.88 GHz. © 2007 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2007.     

Adjoint network method applied to the performance sensitivities of microwave amplifiers

This work focuses on the performance sensitivities of microwave amplifiers using the “adjoint network and adjoint variable” method, via “wave” approaches, which includes sensitivities of the transducer power gain, noise figure, and magnitudes and phases of the input and output reflection coefficients. The method can be extended to sensitivities of the other performance measure functions. The adjoint‐variable methods for design‐sensitivity analysis offer computational speed and accuracy. They can be used for efficiency‐based gradient optimization, in tolerance and yield analyses. In this work, an arbitrarily configured microwave amplifier is considered: firstly, each element in the network is modeled by the scattering matrix formulation, then the topology of the network is taken into account using the connection scattering‐matrix formulation. The wave approach is utilized in the evaluation of all the performance‐measurement functions, then sensitivity invariants are formulated using Tellegen's theorem. Performance sensitivities of the T‐ and Π‐types of distributed‐parameter amplifiers are considered as a worked example. The numerical results of T‐ and Π‐type amplifiers for the design targets of noise figure F_req = 0.46 dB ? 1,12 and V_ireq = 1, G_Treq = 12 dB ? 15.86 in the frequency range 2–11 GHz are given in comparison to each other. Furthermore, analytical methods of the “gain factorisation” and “chain sensitivity parameter” are applied to the gain and noise sensitivities as well. In addition, “numerical perturbation” is applied to calculation of all the sensitivities. © 2006 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2006.     

Nonlinear ceramics for tunable microwave devices

The research on materials and systems for tunable microwave devices has gained attraction within the last years. The radio frequency characterization and the component design of tunable microwave components based on dielectric ceramics especially barium-strontium-titanate (BST) are presented in this second part, whereas the basic material properties are discussed in detail in the first part. After a short introduction to the processing technology used for the fabrication of tunable components based on a BST thick film, the relations between microwave properties and material properties as well as the microstructure are presented in detail. The design process for tunable microwave components based on BST thick films is described. Especially the considerations related to micro- and macrostructure and their connection are highlighted. The paper closes with two different application examples: a reconfigurable array antenna for satellite communication and varactors for high power applications.     

Large‐signal modeling methodology for GaN HEMTs for RF switching‐mode power amplifiers design

A large‐signal model for GaN HEMT transistor suitable for designing radio frequency power amplifiers (PAs) is presented along with its parameters extraction procedure. This model is relatively easy to construct and implement in CAD software since it requires only DC and S‐parameter measurements. The modeling procedure was applied to a 4‐W packaged GaN‐on‐Si HEMT, and the developed model is validated by comparing its small‐ and large‐signal simulation to measured data. The model has been employed for designing a switching‐mode inverse class‐F PA. Very good agreement between the amplifier simulation and measurement shows the validity of the model. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.