A new multiharmonic loading method for large-signal microwave andmillimeter-wave transistor characterization

A multiharmonic loading method for nonlinear microwave and millimeter-wave transistor characterization using six-port techniques is presented. The system allows independent load tuning of an excitation signal and its harmonics. Load-pull measurements on a MESFET which have been performed at the fundamental frequency f₀ and at the second (2f₀) and third (3f₀ ) harmonics are discussed. The results highlight the importance of such measurement in designing and modeling nonlinear devices and circuits. The experimental results are found to be directly applicable for optimizing efficiency and output power in high-power MESFET amplifiers and MESFET frequency multipliers     

Broadband GaAs MESFET and GaN HEMT resistive feedback poweramplifiers

We report 0.2 to 6-GHz MMIC power amplifiers with 12-dB gain, over 23-dBm output power, and more than 25% power-added efficiency (PAE) in a GaAs MESFET technology offering 18 GHz f_τ and 12-V breakdown. These circuits have gain-bandwidth products of ~1.3·f _τ and are more efficient than distributed power amplifiers. A first demonstration of similar circuits in GaN/AlGaN HEMT technology yielded 11-dB gain, 0.2 to 7.5-GHz bandwidth amplifiers with over 31.5-dBm output power and up to 15% PAE. With improved devices and models we expect significantly higher power from the GaN HEMT circuits     

微带线碳化硅E类功率放大器设计

SiC MESFET由于其高击穿电压和低输出电容,适合用于设计E类功率放大器.设计了一种结构简单的微带线拓扑E类负载网络,可以匹配至标准电阻,且抑制高至5阶的谐波.用ADS软件进行电路仿真,在2.14 GHz频率点下,峰值功率附加效率(PAE)为70.5%,漏极效率可达80%,功率增益约为10 dB.     

大信号设计GaAs MESFET功率合成

利用ＧａＡｓＭＥＳＦＥＴ功率特性的线性化模型，求出ＧａＡｓＭＥＳＦＥＴ近似最佳功率负载阻抗，为利用谐波平衡法计算提供初值。然后，使用自行研制的谐波平衡分析软件包，进行ＧａＡｓＭＥＳＦＥＴ大信号模型参数的提取和非线性电路模拟计算。将两只总栅宽为９．６ｍｍ的ＧａＡｓＭＥＳＦＥＴ管芯，利用内匹配功率合成技术，在Ｃ波段（５．５～５．８ＧＨＺ）制成１ｄＢ压缩功率大于８Ｗ，典型功率增益９ｄＢ的ＧａＡｓＭＥＳＦＥＴ内匹配功率管。     

基于GaN器件的连续型高效宽带功率放大器设计*

提出一种高效宽带功率放大器的设计方法,并基于GaN HEMT 器件CGH40010F 设计了验证电路。利用功放管输出寄生参数的等效网络,将基于连续型功放理论得到的负载阻抗转换到封装参考面上,并利用多谐波双向牵引技术对转换后的负载阻抗进行适当调整,使二次谐波负载阻抗位于高效率区以及基频负载阻抗能够获得高功率附加效率和高输出功率。谐波阻抗位于高效率区使得匹配网络的设计简化为基频匹配网络的设计,降低了对谐波阻抗匹配的难度和宽带匹配网络设计的复杂度。实验结果表明:在1GHz -3GHz 工作频带(相对带宽100%)内,功率附加效率在53%-64.6%之间,输出功率为39.5±2dBm,增益为11.5±2dB,二次谐波小于-15dBc,三次谐波小于-25dBc。     

Multiharmonic source-pull/load-pull active setup based on six-port reflectometers: influence of the second harmonic source impedance on RF performances of power transistors

An original measurement system for nonlinear RF power-transistor characterization is presented. This new setup enables the measurement and optimization of output power and/or power-added efficiency (PAE) using active harmonic tuning and six-port reflectometers as vector network analyzers. Two active loops are inserted at both ports of transistors in order to independently control the source and load impedances at the fundamental and at the second harmonic frequency. To the authors' knowledge, this is the only active technique that allows a complete automated multiharmonic load-pull/source-pull measurement system. Experimental results are shown for a commercial GaAs MESFET power transistor at 2 GHz.     

L频段电流型D类功率放大器设计与实现

电流型D类功率放大器与传统电压型D类功率放大器相比,能够消除由非线性寄生电容所带来的功率损耗,因而取得更高的效率和适用于更高的频率段。在L频段实验仿真设计电流型D类放大器的电路并对其电路进行性能分析,最后实现了在1GHz频率点电流型D类功放电路,采用LDMOS场效应管,实际合成输出功率为8.3W,功率增益为14.2dB,漏极效率可达64.8%。     

X-band 0.5, 1, and 2 watt power amplifiers with markedimprovement in power-added efficiency

Very efficient X-band MESFET power amplifiers, showing greater power-added efficiency over a wider bandwidth than any X-band amplifiers of comparable output reported to date, are discussed. The amplifiers were designed with attention given to optimum bias, proper harmonic termination, and efficient power combining. These device and design issues are discussed, and a straightforward design method which achieved the increased levels of efficiency is described     

Nonlinear Circuit Design Using the Modified Harmonic Balance Algorithm

A modification to a harmonic balance algorithm allows the nonlinear analysis of circuits driven by two nonharmonically related input frequencies. The algorithm was implemented on an IBM AT Personal Computer. Three examples are presented to illustrate the analysis. The first is a novel wide-band FET frequency doubler that achieves an average conversion loss of 3.5 dB over the 8-16-GHz output band. The second example illustrates a technique used in the design of a C-band power amplifier in which third-order intermodulation distortion was reduced by 8 dB with two tones of 34 dBm each at the output. The final example illustrates the gain suppression of a smaller tone in the presence of a larger one of slightly different frequency in a limiting amplifier. Simulations agree with measurements in which 2.5-dB gain suppression was observed in a 2-GHz FET feedback amplifier driven into saturation.     

Design of GaAs MESFET Oscillator Using Large-Signal S-Parameters

A design method of GaAs MESFET oscillator using large-signal S-parameters has been discussed. Together with the measurement results of the dependence of Iarge-signall S-parameters on power levels and bias conditions, computer analysis of the equivalent circuit for MESFET'S has qualitatively clarified the large signal properties of MESFET'S. On the basis of these findings, S-parameters have been designed for the MESFET oscillator over the frequency range of 6-10 GHz, which has resulted in power output of 45 mW at 10 GHz with 19-percent efficiency, and 350 mW at 6.5 GHz with 26-percent efficiency, respectively. Good agreements between predicted and obtained performances of MIC positive feedback oscillator have been ascertained, verifying the validity of the design method using large-signal S-parameters.     

A planar 4.5-GHz DC-DC power converter

In this paper, we present two DC-DC converters that operate at a microwave frequency. The first converter consists of a class-E switched-mode microwave amplifier, which performs the DC-AC conversion, and two half-wave diode rectifier outputs. The class-E MESFET amplifier has a minimum power-added efficiency of 86%, corresponding drain efficiency of 95%, and 120 mW of output power at 4.5 GHz. The diode rectifier has a maximum conversion efficiency of 98% and an overall efficiency of 83%. The second converter consists of a high-efficiency class-E oscillator and a diode rectifier. The class-E oscillator has a maximum efficiency of 57% and maximum output power of 725 mW. The DC-DC converter is planar and compact, with no magnetic components, and with a maximum overall DC-DC conversion efficiency of 64% for a DC input of 3 V, and the output voltage across a 87-Ω load of 2.15 V     

GaAs laser amplifiers

Experimental results are presented on the operational characteristics of GaAs laser amplifiers very closely coupled to a laser oscillator. The separation between the oscillator and the amplifier was varied from 0.2 to 2.0 microns. The amplifiers were made by lapping one end at an angle of 10 to 15 degrees. This angle is several times larger than the critical angle for confinement of radiation in GaAs lasers that is estimated from experimental data to be between 2 and 3 degrees. The measured signal gain is a decaying function of input power and approaches a value of 2 to 4 for large input signals. A maximum amplifier gain of about 150 was obtained for an input signal of 2 mW/mil junction width (corresponding to an optical flux-density of about 8 kW/cm²incident on the input side of the amplifier). At this input power level, the output fluoresence is reduced by about 50 percent and the internal oscillatory modes of the amplifier are almost completely quenched. The ratio of the oscillator output actually coupled into the amplifier to the measured output from the oscillator was estimated from gain saturation measurements. It was found to be inversely proportional to the cleaved separation between the oscillator and the amplifier and was estimated as 0.5 and 0.07 for separations of 0.2 and 2 microns, respectively. The output quantum efficiency of the laser amplifier was demonstrated to be comparable to the output quantum efficiency of a single oscillator. Tests of a new structure for a low-noise, constant-gain laser amplifier are described.     

Power optimization of high-efficiency microwave MESFET oscillators

Achieving high output power and efficiency in GaAs MESFET oscillators is mainly hampered by the device's parasitics, its static I-V characteristics, and the circuit embedding impedance. In this paper, the derivation of the relationship between oscillator output power and various circuit and device parameters is presented. From these analytical expressions, optimum operating conditions for maximum oscillator output power and efficiency are determined. The analysis method employed here is based upon a quasi-linear approach and an open-loop model of the oscillator. The design procedure is verified by measurements on an experimental circuit, which have demonstrated a dc/radio-frequency conversion efficiency of 54%     

高精度CMOS DEM-CCⅡ放大器

采用动态元件匹配二代电流传输器(DEM-CCⅡ)技术,设计了一种0.35μm标准工艺的高精度CMOS放大器。通过比较传统的CMOS运放可知,所设计的CMOS放大器既增大了输出摆幅又减小了输出阻抗,且有效地限制了有限的运放增益对电路性能的影响。仿真实验结果表明,该CMOS放大器增益误差比传统运放的增益误差小38～50倍,精度等级明显提高,因而特别适用于各类检测和信号调理放大器的设计中。     

High efficiency and high linearity InGaP/GaAs HBT power amplifiers:matching techniques of source and load impedance to improve phasedistortion and linearity

This paper reports on a matching technique of the source and load impedance focused on a phase distortion of InGaP/GaAs HBT power amplifiers to simultaneously achieve a high efficiency and a high linearity performance. Load-pull measurements were done to maximize power added efficiency (PAE) and source pull measurements to minimize the phase distortion and adjacent channel leakage power (ACP). Our HBT exhibited a high PAE of 60.7% and an ACP at a 50 kHz offset frequency of -51 dBc for 1.5 GHz π/4-shift QPSK modulated signal with an output power (P_cut) of 31 dBm under a supply voltage of 3.5 V     

HIgh-Power C-Band Multiple-IMPATT-Diode Amplifiers

The design considerations and performance characteristics of two high-power microwave reflection amplifiers that use multiple silicon IMPATT diodes are presented. The amplifiers employ microstrip hybrid-circuit-type power combiners to combine the individually matched IMPATT diodes. The first unit, a single-stage 4-diode amplifier, produced 8-W output with 6-dB gain while the second 12-diode amplifier gave 15.8-W output at about 9-dB gain. FM and AM noise added by these amplifiers has been measured with each amplifier driven to nearly full output. Use of microstrip hybrid-circuit power combiners appears to offer a simple and economical design approach for the implementation of microwave solid-state power amplifiers using multiple active devices.     

Switched-capacitor FSK modulator and demodulator in CMOS technology

A switched-capacitor FSK modulator/demodulator built in silicon-gate CMOS technology is described. The modulator is based on a programmable harmonic oscillator using two stray-insensitive integrators. The centerpiece of the FSK demodulator is a switched-capacitor voltage-controlled oscillator. A simple post-detection processor restores the digital data. Both circuits have been designed for the 600-baud modem channel with 1500 Hz center frequency and /spl plusmn/200 Hz frequency shifts, but the demodulator operates in the 1200-baud channel as well. Due to dynamic biasing the operational amplifiers feature high slew rate, high voltage gain, and low power for capacitive loads.     

两级GaAs单片功率放大器

本文报道了两级GaAs单片功率放大器的设计和制作,着重介绍了利用MESFET的小信号模型和直流负载特性设计MESFET在大信号状态下的最佳功率匹配的方法,该方法大大简化了放大器匹配电路的设计.制作在1.9×0.9mm GaAs外延片上的两级放大器,1dB带宽800MHz(670～1470MHz)频带内,最大小信号增益24dB,最大输出功率300mW.功率附加效率17.8%.     

New Measurement Methods of Dominant-Pole-Type Operational Amplifier Parameters

New simple and easy methods measuring the parameters of operational amplifiers (OA's) are presented with newly constructed testing circuits and setups. Firstly, it is shown that the transition frequency and dominant-pole frequency are derived from a relaxation or harmonic oscillator in which the OA under test is used as an element of the circuit. Secondly, it is shown that other parameters such as the open-loop gain, the input and output resistance, the input offset voltage, the input bias current, and the input offset current are obtained easily from the new circuits.     

用VOLTERRA 级数精确分析 MESFET 功率放大器的副谐波负载牵引特性

为了分析CDMA类宽带信号激励下MESFET功放的副谐波负载牵引特性,推导了一组基于MESFET非线性模型的功放电路Volterra转移函数解析式,利用此解析式,建立了三阶交调分量与副谐波负载的解析关系,分析了不同副谐波负载情况下副谐波牵引特性;并推导出了最优副谐波负载的表达式。该文还从两个三阶交调幅度的差异着手,证明了电抗性副谐波负载是造成这一差异的主要因素,上述推导得到的结果与采用ADS软件谐波平衡法仿真得到的结果吻合得很好。