A Nonlinear GaAs FET Model for Use in the Design of Output Circuits for Power Amplifiers

A nonlinear equivalent circuit model for the GaAs FET has been developed based upon the small-signal device model and separate current measurements, including drain-gate avalanche current data. The harmonic-balance technique is used to develop the FET RF load-pull characteristics in an amplifier configuration under large-signal operation. Computed and experimental load-pull results show good agreement.     

GaAs MESFET modeling and nonlinear CAD

Equivalent circuit modeling techniques are described for both small-signal and large-signal models of GaAs MESFETs. The use of large-signal model in an interactive program for amplifier analysis is shown. The computed load-pull results and IMD (intermodulation distortion) predictions are shown to be in good agreement with measured data at 10 GHz     

Table-based nonlinear HEMT model extracted from time-domain large-signal measurements

This paper presents an empirical table-based nonlinear HEMT model fully extracted from time-domain large-signal measurements. A simple and direct extraction procedure, based on a vector nonlinear network analyzer measurement system with load-pull facilities, demonstrates by experimental results on microwave transistors how a very reduced number of measurements is enough to obtain the current and charge generators to fill a lookup model. Table-based model extraction, implementation, and validation are described in this paper.     

RF Characterization of Microwave Power Fet's

The large-signal S-parameter S/sub 22/ and the optimum load for maximum output power are two parameters commonly used in the RF characterization of microwave power FET's. Using a nonlinear circuit model of the device, the dependence on RF power of each of these parameters is investigated. A method is given for computing the optimum load from the Iarge-signal S/sub 22/. Equivalent load-pull data can thus be obtained without the need for load-pull measurements. The gain compression characteristics of the transistor for arbitrary load can be computed from large-signal S/sub 21/, and S/sub 22/ data.     

Mildly Nonquasi-Static Two-Port Device Model Extraction by Integrating Linearized Large-Signal Vector Measurements

This paper introduces a new procedure, based on linearized large-signal vector measurements, for extracting a nonlinear behavioral model for two-port active microwave devices. The technique is applied to a model structure that assumes a short-term memory condition and is formulated as a parallel connection of a limited number of frequency-weighted static nonlinearities. The proposed method consists of integrating the time-varying linear characterization of the device driven into a nonlinear state by a large signal. The experiment design and measurement setup are based on a large-signal network analyzer and are discussed in detail. In the second portion of this paper, insight is provided on the most meaningful model parameters, along with an extensive independent experimental validation, which considers a GaAs pHEMT as a case study and includes two-tone large-signal data, a wideband code division multiple access signal, bias-dependent -parameters, and dc data.     

Microwave measurements - Part III: Advanced non-linear measurements

This work completes the sequence started with articles [1] and [2], previously published in this journal, which presented the most important aspects of RF and microwave linear and non-linear measurements. In [1], some off-the-shelf linear measurement approaches at microwaves were described, whereas [2] showed the conventional characterization of non-linear devices under large-signal conditions, such as active and passive load-pull at fundamental and harmonic frequencies. In basic load-pull systems, the device under test (DUT) is driven by a single tone microwave source while the DUT performance metrics, typically output power and power added effi ciency (PAE), are monitored as a function of the load and/or source terminations. This strategy enables the straight-forward identifi cation of the optimum input and output loads. In this article, we describe two of the most advanced measurement techniques that can provide the required information for power amplifi er design and transistor modeling. The first technique is the multi-tone/complex modulation load-pull. It is useful especially for wireless applications, where conventional single tone excitations do not give suffi cient information for model and design development. The measurement conditions would be too far from the typical working ones. The second measurement technique is the timedomain waveform load-pull. Its applications span from highly accurate and reliable device model extraction to monitoring of actual operating conditions and "waveform engineering" for high-performance design.     

Hot small-signal S-parameter measurements of power transistors operating under large-signal conditions in a load-pull environment for the study of nonlinear parametric interactions

This paper presents a setup that enables wide-band (in-band and out-of-band) measurements of hot small-signal S-parameters of nonlinear devices driven by a large-signal single tone (namely, the pump signal). A load-pull characterization is performed at the pump frequency (F/sub 0/), while hot small-signal S-parameters are measured with a perturbating signal at a frequency (f) by the use of a probe tone. Basically, the frequency of the probe tone is swept over a wide bandwidth (at the present time from 300 MHz up to F/sub 0//2). A higher frequency range, from near dc to KF/sub 0/, will be implemented in a similar manner. The measurement setup reported here is applied to on-wafer measurements of S-band HBTs. Hot small-signal S-parameter measurements versus large-signal load impedance and pump level will be shown. An application to the prediction of parametric oscillations will be demonstrated. A parametric oscillation predicted at 373 MHz is confirmed by spectrum measurements.     

Systematic linearity analysis of RFICs using a two-port lumped-nonlinear-source model

A frequency-domain lumped-nonlinear-source behavioral model is presented. This generalized two-port nonlinear model is used to characterize the linearity of either RF devices or circuits. Similar to two-port ac behavioral models (i.e., using S-, Y-, Z-, or H-parameters), this nonlinear model supports combinations such as shunt, series, and cascade, and thus is suitable for systematic analysis. This model is then applied to analyze the impact of harmonic impedance on the second-order intermodulation and third-order intermodulation of a state-of-the-art SiGe HBTs and circuits. Simple and general linearity expressions are then derived. Harmonic load-pull simulations and measurements are used to demonstrate the usefulness of the proposed analysis technique.     

Simultaneous load-pull of intermodulation and output power undertwo-tone excitation for accurate SSPA's design

The simultaneous measurements of the third-order intermodulation and output power under two-tone excitation have been implemented on a MESFET operated in large-signal mode for load impedances spanning quasi-entirely the Smith chart, using a six-port reflectometer with variable test port impedance. An experimental comparison between single-tone and two-tone output power and power-added efficiency was performed. The experimental results show that the load-pull of the output power capability and power-added efficiency by a two-tone test are more accurate than the single-tone characterization for multi-carrier Solid State Power Amplifiers (SSPA's) design     

负载牵引法在开关类功率放大器设计中的应用

为提高开关类功率放大器设计的准确性,找出功放管的最优输出阻抗值,采用负载牵引法设计开关类功率放大器,得到最佳输出阻抗值,然后设计输出及输入匹配网络及谐波抑制网络,仿真结果输入功率为28dBm时,功率附加效率达到69．352％,表明功率负载牵引方法为改进开关类放大器设计,优化开关类功放管性能提供了快速而有效的方法,提高了大信号下模型的准确性。     

Direct extraction of nonlinear FET C-V functions from time domainlarge signal measurements

A simple technique for extracting the nonlinear intrinsic capacitances in a quasi-static HEMT model from large signal time domain microwave measurements is presented. This method is based on the use of a suitable load-pull configuration around a vector nonlinear network analyser     

Discrete-time parametric amplification based on a three-terminal MOS varactor: analysis and experimental results

This paper discusses discrete-time parametric amplification based on large-signal operation of a three-terminal MOS varactor. The principle of operation is described in detail and analytical estimates of performance are derived. Detailed measurements are reported for a prototype implemented in standard digital CMOS technology. It is demonstrated that the technique can be used to provide micropower, low-gain, low-noise, large-signal amplification.     

一种基于贝叶斯推理的微波器件阻抗调谐算法

阻抗调谐匹配是设计和优化微波毫米波收发电路不可或缺的关键技术之一.为解决有源负载牵引稳定度差、调谐速度慢的问题,提出了一种利用基于贝叶斯推理的行为级模型进行阻抗调谐的算法.该技术可有效减少负载阻抗合成过程所需的迭代次数,提高阻抗合成精度,从而有效提升有源负载牵引技术的实用性和稳定性.为验证该算法的有效性,搭建了有源实时...     

Straightforward and accurate nonlinear device model parameter-estimation method based on vectorial large-signal measurements

To model nonlinear device behavior at microwave frequencies, accurate large-signal models are required. However, the standard procedure to estimate model parameters is often cumbersome, as it involves several measurement systems (DC, vector network analyzer, etc.). Therefore, we propose a new nonlinear modeling technique, which reduces the complexity of the model generation tremendously and only requires full two-port vectorial large-signal measurements. This paper reports on the results obtained with this new modeling technique applied to both empirical and artificial-neural-network device models. Experimental results are given for high electron-mobility transistors and MOSFETs. We also show that realistic signal excitations can easily be included in the optimization process.     

A CAD-oriented nonlinear model of SiC MESFET based on pulsed I(V),pulsed S-parameter measurements

In order to use SiC devices in CAD nonlinear circuits, a nonlinear model of 4H-SiC MESFET has been obtained using a technique based on pulsed I(V) characteristics and pulsed S-parameter measurements. The nonlinear I-V drain-source current was represented using a table-based model which was implemented in a harmonic balance simulator. Its accuracy is shown by a comparison with active load-pull measurements     

基于神经网络的GaAs HBT器件模型研究

建立精确的模型是使用砷化镓异质结双极晶体管器件（GaAs HBT）设计集成电路的必要基础,传统经验模型建立过程复杂,在输出功率、增益、功率附加效率等功率特性方面的模拟精度不太高,给电路设计带来了一定的难度。本文利用径向基函数(RBF)神经网络算法和反向传播(BP)神经网络算法分别建立GaAs异质结双极晶体管器件的大信号模型。这些模型的训练和测试数据分别来自于测试的双端口散射参数,以及测试的直流特性和功率特性数据。然后将模型数据与实测结果进行对比,结果发现,基于神经网络的器件模型能够精确地模拟器件特性,而且RBF神经网络模型相比BP神经网络模型,误差更小,预测更精确。     

功率FET和二极管大信号建模方法

Under a large signal drive level,a frequency domain black box model of the nonlinear scattering function is introduced into power FETs and diodes.A time domain measurement system and a calibration method based on a digital oscilloscope are designed to extract the nonlinear scattering function of semiconductor devices.The extracted models can reflect the real electrical performance of semiconductor devices and propose a new large-signal model to the design of microwave semiconductor circuits.     

Large-signal modeling method for power FETs and diodes

Under a large signal drive level, a frequency domain black box model of the nonlinear scattering function is introduced into power FETs and diodes. A time domain measurement system and a calibration method based on a digital oscilloscope are designed to extract the nonlinear scattering function of semiconductor devices. The extracted models can reflect the real electrical performance of semiconductor devices and propose a new large-signal model to the design of microwave semiconductor circuits.     

Nonlinearity and cross modulation in field-effect transistors

It is shown that present large-signal models are inadequate for cross modulation in field-effect transistors, but the cross-modulation performance can be accurately predicted from a power-series approximation to the measured l.f. transfer characteristic of the device. The cross modulation for typical field- effect transistors is essentially independent of frequency up to about 100 MHz. A large-signal h.f. model of the field-effect transistor is proposed for the prediction of cross modulation and related phenomena at very high frequencies. Computer predictions of cross modulation based on this model agree well with experimental measurements.     

A large-signal physical MESFET model for computer-aided design andits applications

A quasi-static, large-signal MESFET circuit model is presented. It is based on a comprehensive quasi-two-dimensional, semiclassical, physical device simulation, and its unique formulation and efficiency make it suitable for the computer-aided design of nonlinear MESFET subsystems. Using this approach the semiconductor equations are reduced to a consistent one-dimensional approximation requiring substantially less computing resources than a full two-dimensional simulation. CPU time is typically reduced by a factor of 1000. A single/two-tone harmonic balance analysis procedure which uses the describing frequency concept is also developed and combined with the MESFET model. Numerical load-pull contours as well as intermodulation distortion contours have been simulated; their comparison with measured results validates the approach taken