InGaP/GaAs HBT器件的制备及其特性

采用在发射区台面腐蚀时保留InGaP钝化层和去除InGaP钝化层的方法制备了两种InGaP/GaAs异质结双极晶体管(HBT)器件,研究了InGaP钝化层对HBT器件基区表面电流复合以及器件直流和射频微波特性的影响.对制备的两种器件进行了对比测试后得到:保留InGaP钝化层的HBT器件最大直流增益(β)为130,最高振荡频率(fmax)大于53 GHz,功率附加效率达到61％,线性功率增益为23 dB;而去除InGaP钝化层的器件最大β为50,fnax大于43 GHz,功率附加效率为57％,线性功率增益为18 dB.测试结果表明,InGaP钝化层作为一种耗尽型的钝化层能有效抑制基区表面电流的复合,提高器件直流增益,改善器件的射频微波特性.     

InGaP HBT 微波大信号负载线特性

本文研究和分析了先进的InGaP HBT 的大信号和小信号微波动态负载线特性。研究结果显示微波动态负载线形状在大信号下发生畸变。电流极值与电压极值错开。在较大信号下动态负载线电流极值线与小信号的负载线保持一致,在极大信号下动态负载线电流极值线斜率与小信号负载线斜率保持一致。提出了一种简便计算大信号下负载功率的方法。     

5~6GHz自适应线性化偏置的InGaP/GaAs HBT功率放大器

针对高质量无线局域网的传输需求,设计了一款工作在5~6 GHz的宽带磷化镓铟/砷化镓异质结双极型晶体管(InGaP/GaAs HBT)功率放大器芯片。针对HBT晶体管自热效应产生的非线性和电流不稳定现象,采用自适应线性化偏置技术,有效地解决了上述问题。针对射频系统的功耗问题,设计了改进的射频功率检测电路,以实现射频系统的自动增益控制,降低功耗。通过InGaP/GaAs HBT单片微波集成电路(MMIC)技术实现该功率放大器芯片。仿真结果表明,功放芯片的小信号增益达到32 dB;1 dB压缩点功率为28.5 dBm@5.5 GHz,功率附加效率PAE超过32%@5.5 GHz;输出功率为20 dBm时,IMD3低于-32 dBc。     

InGaP异质结双极晶体管ESD特性研究

研究了高速射频集成电路(RF IC)中InGaP异质结双极晶体管(HBT)器件的特性.测试了单指发射极和双指发射极两种结构器件的大信号DC I-V特性及抗人体模型(HBM)静电放电(ESD)能力.结果表明,双指发射极器件比单指器件能传导更高密度的电流,并能抵抗高能量的ESD;两种器件的击穿特性相似.这些结果可以用来指导RF IC ESD保护电路的设计.     

具有在片稳定网络的GaAs HBT微波功率管

采用GaAs标准MMIC工艺制作了具有片上RC并联稳定网络的InGaP/GaAs HBT微波功率管单胞.依据K稳定因子,RC网络使功率管在较宽的频带内具有绝对稳定特性.Load-pull测试表明RC网络没有严重影响功率管的大信号特性,在5.4GHz饱和输出功率为30dBm,在11GHz 1dB压缩点输出功率大于21.6dBm.功率合成电路验证了该功率管具有高稳定性,非常适合制作微波大功率HBT放大器.     

具有在片稳定网络的GaAs HBT微波功率管

采用GaAs标准MMIC工艺制作了具有片上RC并联稳定网络的InGaP/GaAs HBT微波功率管单胞.依据K稳定因子,RC网络使功率管在较宽的频带内具有绝对稳定特性.Load-pull测试表明RC网络没有严重影响功率管的大信号特性,在5.4GHz饱和输出功率为30dBm,在11GHz 1dB压缩点输出功率大于21.6dBm.功率合成电路验证了该功率管具有高稳定性,非常适合制作微波大功率HBT放大器.     

基于Volterra级数的HBT功率放大器负载阻抗的优化设计

利用Volterra级数法,研究了InGaP/GaAs HBT功率放大器的非线性失真,分析了非线性指标IP3和功率放大器负载阻抗的关系,完成了功率放大器负载阻抗的优化设计;采用2 μm InGaP/GaAs HBT半导体工艺进行流片.测试结果表明,设计的功率放大器在不影响输出功率和功率附加效率的前提下,线性度得到较大改善,IP3提高6 dB,与理论分析及计算机仿真结果相吻合.     

一种用于InGaP/GaAs HBT的简化的VBIC模型

提出一个应用于InGaP/GaAs HBT的简化的VBIC模型,描述了模型参数的提取方法,并把此模型应用于单、多指InGaP/GaAs HBT器件的建模.对器件的I-V特性及50MHz～15GHz频率范围内S参数进行了测量和仿真.结果表明,50MHz～9GHz频率范围内,简化后模型可对InGaP/GaAs HBT交流小信号特性进行较好的表征.     

高效率Class F功率放大器的设计

本文基于InGaP/GaAs HBT(HBT为异质结双极晶体管)工艺设计了一款高效率的Class F功率放大器。文中首先描述了F类功率放大器的特点和电路原理,然后对放大器的设计过程如匹配电路设计技术、谐波抑制对功率效率的影响,以及偏置电路的设计等问题做了详细的讨论。测试结果表明,设计的功率放大器在电源电压为5V,输出功率为37dBm时,效率达68%。     

北斗系统射频功率放大器的研究与设计

本文设计了一款可应用于我国北斗卫星导航系统的单片微波集成功率放大器。该功率放大器基于台湾WIN半导体公司的InGaP/GaAs异质结双极型晶体管（HBT）器件Q360模型,仿真结果表明,其在1.5-1.7GHz的工作频率范围内,小信号增益稳定在40dB左右,输入输出反射系数均在-10dB以下,P1dB输出功率为35dBm,大信号功率增益达到36.5dB,效率附加效率（PAE）达到56%,可满足我国北斗系统的常规应用。     

Large signal RF power transmission characterization of InGaP HBT for RF power amplifiers

The large signal RF power transmission characteristics of an advanced InGaP HBT in an RF power amplifier are investigated and analyzed experimentally. The realistic RF powers reflected by the transistor, transmitted from the transistor and reflected by the load are investigated at small signal and large signal levels. The RF power multiple frequency components at the input and output ports are investigated at small signal and large signal levels, including their effects on RF power gain compression and nonlinearity. The results show that the RF power reflections are different between the output and input ports. At the input port the reflected power is not always proportional to input power level; at large power levels the reflected power becomes more serious than that at small signal levels, and there is a knee point at large power levels. The results also show the effects of the power multiple frequency components on RF amplification.     

A hybrid digital/RF envelope predistortion linearization system for power amplifiers

This paper presents an adaptive wide-band digitally controlled RF envelope predistortion linearization system for power amplifiers (PAs). A field-programmable gate-array-based lookup table is indexed by a digitized envelope power signal, and instantaneously adjusts the input signal amplitude and phase via an RF vector modulator to compensate for the AM-AM and AM-PM distortion. The advantages of this predistortion architecture over conventional baseband digital approaches are that a 20%-33% wider correction bandwidth is achievable at the same clock speeds, and linearization can be performed without the need for a digital baseband input signal. The timing match between the input RF signal and predistorting signal, which is one of the critical factors for performance, was investigated and adjusted to obtain optimum performance. Using three-carrier cdmaOne and wide-band multitone signals, the linearization performances for a 0.5-W GaAs heterostructure field-effect transistor, a 90-W peak-envelope-power (PEP) silicon LDMOS PA, and a 680-W PEP LDMOS PA were examined. In addition, the predistortion performance variation for different signals was studied in terms of signal envelope statistics, output powers, and PA power capacities.     

应用于4G-LTE无线通信系统的F类高PAE射频功率放大器

为了有效实现高谐波抑制并提高功率附加效率,提出了一种适用于4G-LTE无线通信系统的高效F类功率放大器。该功率放大器使用了低电压p-HEMT晶体管和小型微带抑制单元,能够在低射频输入功率下产生n次谐波抑制和较高的功率附加效率（power added efficiency,PAE）。采用谐波平衡法对提出的功率放大器进行了仿真分析,并对其进行了实际制造。通过实际测量对仿真结果进行了验证。测量结果显示,提出功率放大器的工作频率为1.8 GHz,带宽为100 MHz,平均PAE为76.9％,且具有2V的极低漏极电压。射频输入功率范围分别为0-12 dBm时,最大输出功率和增益分别为23.4和17.5 dBm。     

High-Efficiency Differential-Drive CMOS Rectifier for UHF RFIDs

A high-efficiency CMOS rectifier circuit for UHF RFIDs was developed. The rectifier has a cross-coupled bridge configuration and is driven by a differential RF input. A differential-drive active gate bias mechanism simultaneously enables both low ON-resistance and small reverse leakage of diode-connected MOS transistors, resulting in large power conversion efficiency (PCE), especially under small RF input power conditions. A test circuit of the proposed differential-drive rectifier was fabricated with 0.18 $mu$ m CMOS technology, and the measured performance was compared with those of other types of rectifiers. Dependence of the PCE on the input RF signal frequency, output loading conditions and transistor sizing was also evaluated. At the single-stage configuration, 67.5% of PCE was achieved under conditions of 953 MHz, ${-}$ 12.5 dBm RF input and 10 K$Omega$ output load. This is twice as large as that of the state-of-the-art rectifier circuit. The peak PCE increases with a decrease in operation frequency and with an increase in output load resistance. In addition, experimental results show the existence of an optimum transistor size in accordance with the output loading conditions. The multi-stage configuration for larger output DC voltage is also presented.      

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.     

磁共振系统中微型射频功率电桥的设计与测试

射频前端系统是影响核磁共振系统成像的关键部件之一。基于射频功率电桥的设计原理,在传统的FR4基板上采用集总工艺方法,实现微型化的射频功率电桥,仿真和测试结果显示,微尺度功率电桥的耐流、耐压性能优异,信号精度高,同时在核磁共振系统的工作频率下,小信号和大信号的输出损耗很小,完全符合核磁共振系统对大功率电桥的需求,整体的性能优异。     

一种射频可编程N分频器的设计

提出了用射频CML技术设计的2/3分频单元.基于2/3分频单元,使用0.35 μm SiGeBiCMOS工艺,实现了射频可编程N分频器.验证结果表明,电路可在GHz频率下正常工作,具有相噪低、功耗小等特点.在3 GHz射频输入信号频率下,频偏100 kHz的输出相位噪声为-143dBc/Hz.电路消耗的总电流仅为4 mA(3 V单电源电压),功耗仅为12 mW.     

A Discrete‐Amplitude Pulse Width Modulation for a High‐Efficiency Linear Power Amplifier

A new discrete‐amplitude pulse width modulation (DAPWM) scheme for a high‐efficiency linear power amplifier is proposed. A radio frequency (RF) input signal is divided into an envelope and a phase modulated carrier. The low‐frequency envelope is modulated so that it can be represented by a pulse whose area is proportional to its amplitude. The modulated pulse has at least two different pulse amplitude levels in order that the duty ratios of the pulse are kept large for small input. Then, an RF pulse train is generated by mixing the modulated envelope with the phase modulated carrier. The RF pulse train is amplified by a switching‐mode power amplifier, and the original RF input signal is restored by a band pass filter. Because duty ratios of the RF pulse train are kept large in spite of a small input envelope, the DAPWM technique can reduce loss from harmonic components. Furthermore, it reduces filtering efforts required to suppress harmonic components. Simulations show that the overall efficiency of the pulsed power amplifier with DAPWM is about 60.3% for a mobile WiMax signal. This is approximately a 73% increase compared to a pulsed power amplifier with PWM.     

The class BD high-efficiency RF power amplifier

Class B and class D operation of the same RF power amplifier circuit is not normally possible because of constraints imposed by the tuned output circuit and DC power input circuit. The use of square-wave drive in a current switching class D RF amplifier circuit allows the amplifier to move gradually from current source to current switch operation. This amplifier, called class BD, has a linear transfer characteristic (drive envelope to output envelope) and an efficiency 1.23 times that of a class B RF amplifier with the same peak output. The addition of a resistive AC current path to ground in the DC power input circuit of the class BD RF amplifier allows operation with sinewave driving waveforms. While this lowers the efficiency at the peak output, it can raise it at lower outputs, making possible a factor of 1.57 improvement in efficiency in the amplification of signals with large peak-to-average ratios. The class BD RF amplifier may therefore be used as a broad-band replacement for a Doherty-type amplifier.     

用于微波放大器的InGaP HBT微波动态大信号波形特性

In wireless mobile communications and wireless local area networks （WLAN）, advanced InGaP HBT with power amplifiers are key components. In this paper, the microwave large signal dynamic waveform characteristics of an advanced InGaP HBT are investigated experimentally for 5.8 GHz power amplifier applications. The microwave large signal waveform distortions at various input power levels, especially at large signal level, are investigated and the reasons are analyzed. The output power saturation is also explained. These analyses will be useful for power amplifier designs.