一种应用于IFM的新型鉴相器设计

介绍了对数放大器AD8309在瞬时测频(IFM)中的应用,设计了基于AD8309的一种新型鉴相器电路,并将该电路成功应用于某跟踪本振的瞬时测频单元中。实现了对输入射频信号频率298~318 MHz、功率为-50~+20 dBm、脉冲调制信号宽度为150 ns条件下,测频精度150 kHz、准确度≤±300 kHz的技术指标。具有工作射频脉冲调制脉冲小、工作动态大等优点。     

高增益S波段小型化200 W功率模块研制技术

采用多级射频放大电路以及高压脉冲调制技术,实现了S波段高增益小型化200 W功率模块的研制。驱动放大电路采用GaAs功率单片进行功率合成;末级放大电路依托栅长(0.5 μm) GaN高电子迁移率晶体管(HEMT)芯片,选取多子胞结构来改善热分布,通过内匹配技术设计完成了双胞总栅宽24 mm GaN芯片的匹配网络,并设计高压脉冲调制电路提供电源,成功研制出了小型化的S波段200 W内匹配GaN功率模块。测试得出该模块实现了在输入功率10 dBm,栅极电压-5 V,漏极电压32 V,TTL调制信号输入条件下,输出频率在3.1~3.5 GHz处,输出功率大于200 W,功率附加效率(PAE)大于55%。模块实际尺寸为2.4 mm×38 mm×5.5 mm。     

射频信号源的设计

本文采用以高频头FI1256为本振,结合外围分频、增益控制及功率放大器电路,实现10MHz～900MHz射频信号的频率和功率连续可调,输出功率在2dBm～-10dBm之间可调。本设计具有高性价比,频率稳定度高,谐波分量和相位噪声的抑制效果良好等优点,是一款良好的实用型射频信号源。     

中小功率20～120MHz射频CO_2激光电源信号发生器的研究

本文介绍了中小功率(激光器连续输出功率100W以下)激光电源信号发生器的发展概况、选择原则,并详细介绍了20～120MHz射频CO_2激光电源信号发生器之一的晶体振荡器电路原理及实用电路,讨论了其调试方法及注意事项.它的主要技术指标是:工作频率f为20～120MHz,最大连续输出功率W=4mW,且连续可调,频率稳定度Δf/f=10~(-4).     

带有低噪声单端转差分电路的射频增益可控放大器

为了改进传统电路中单端转差分电路的噪声性能,提高传统射频可变增益放大器的覆盖范围和步进精度,该文设计了一种带有低噪声单端转差分电路的射频增益可控放大器。该文利用噪声抵消技术降低了噪声系数,利用电容交叉耦合技术展宽电路带宽,利用输出源级跟随器的增益可调功能实现更高的步进精度。电路采用0.18 mm CMOS工艺,1.8 V供电电源,在170-870 MHz频率信号输入下,可以实现最低3.8 dB的噪声系数,55 dB的动态范围,步进精度0.8 dB,消耗14.76 mW的功耗,面积800 mm×600 mm。测试结果表明在覆盖更宽的频段范围下,该文设计的射频可变增益放大器在消耗相同功率条件下与传统的单端转差分电路相比可以达到更低的噪声系数,同时整个可变增益放大器可以提供更高的步进精度。     

可扩展分频比范围的射频可编程分频器设计

介绍了一种可扩展分频比范围的射频可编程分频器,该电路包括输入放大器、前置2分频电路、4级除2/除3分频单元和15位可编程计数器。该分频器应用于频率合成器中,采用0.35μm BiCMOS工艺实现,电源电压3.3V,电源电流80mA。射频输入12GHz时灵敏度-10~10dBm。分频比从16到219-1可调。     

基于PWM大功率超声波电源的设计

本文详细介绍了为驱动磁滞伸缩换能器而设计的一种频率、功率可调式大功率超声波电源,该电源采用由IGBT构成的全桥式逆变主电路,实现了逆变降压和输出电压调控。控制电路以脉宽调制电路为核心,通过给定信号和反馈信号电压的比较,获得宽度可变的脉冲信号,调节电源的输出电压,并实现对电源的闭环控制。     

一种采用频率变换的自供电电源管理电路

 在低频率条件下,采用直接阻抗匹配的原理,设计的压电材料换能器电源管理电路,匹配电感值很大.本文采用频率变换,设计了一种自供电电源管理电路.分析了频率变换的原理.将低频信号变换至较高频率,匹配电感值很小,有利于电路的小型化.该管理电路还可以在宽频带内对于压电换能器实现匹配.实验结果表明,电路实现了频率变换,匹配电感值和电路体积都大大减小.电源管理电路的最大采集功率为181.6mW,能量采集效率可以达到44.8%.当0.47法拉的储能电容电压为1.13V时,该电路最大放电功率可达110mW,放电时间持续620ms,能够驱动无线传感器在一个周期内正常工作.     

一种双耦合双混频中频信号功率反馈电路

在自动电平控制系统中,常用功率反馈电路存在一个主要限制:调幅动态范围受限于电平检波器和相关电路,使其远远低于线性调制器的功率可变范围。文中介绍了一种双耦合双混频中频信号功率反馈电路,使检波器只需检测固定中频信号的功率大小即可反馈调节射频输出信号的功率幅度。经测试,电路射频输入信号在24 GHz变化时,得到的中频信号频率固定不变,等于晶振信号54 MHz。线性调制器的衰减量在031.5 dB变化时,中频信号功率与射频输出信号功率成良好的线性关系,满足预期的设计要求。     

多路输出单端反激式开关电源设计

在阐述了基于TOPSwitch系列芯片设计的单片反激式开关电源原理的基础上，详细介绍了一种用于智能仪表小功率多输出AC／DC开关电源的设计方法。该电源主电路采用反激式电路，应用反馈手段和脉冲调制技术实现多路电压的稳定输出。最后，给出了实验结果。试验表明，该电源具有良好的性能。     

微波大功率变脉冲放大器的研制

针对基于悬浮平台微波凝视关联成像系统对变脉冲宽度和大峰值功率的需求,研制了一款 X 波段变脉冲固态功率放大器。描述该放大器组件中高速漏极调制及保护电路和射频开关的实现方案,分析大功率高速漏极调制电路输出电压脉冲的影响因素,优化调制电路的负载设计,并解决功放输出射频脉冲的包络凹陷问题。经试验验证:研制的功率放大器具有散热性好,稳定工作时间长,最窄脉宽 20 ns,上升下降沿均小于 3 ns,峰值功率大于 40 W 的射频脉冲输出等特点;其漏极调制电路输出 24 V电压脉冲,上升沿小于 20 ns,下降沿约 60 ns。     

P波段1．3kW宽带发射机

介绍了一种P波段1．3kW宽带发射机。该发射机采用第六代LDMOS场效应晶体管作为末级放大管,采用有耗网络设计功率管的输入、输出匹配电路,对漏极供电电源用于射频同步的脉冲进行调制,实现了高增益、宽带宽和高效率。该发射机结构紧凑,工作可靠。     

Dual-Gate MESFET Variable-Gain Constant-Output Power Amplifier

The use of a dual-gate GaAs FET as a broad-band variable gain and constant output power amplifier is described. A five-stage variable gain-constant output power amplifier has been realized which provides a constant output power of 3 dBm (/spl plusmn/2 dB) for a large dynamic range of input power of -45 dBm to 0 dBm over the 4-8-GHz band. The amplifier uses a feed-forward AGC circuit for preadjusting the gain of the amplifier stages depending upon the strength of the signal at the output of preceding stages. The amplifier has the capability of detecting two or more simultaneous RF pulses having different amplitudes and separated by more than 15-ns time intervals. Also it preserves any amplitude modulation of the individual pulse.     

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.     

A 1.75-GHz polar modulated CMOS RF power amplifier for GSM-EDGE

This work presents a fully integrated linearized CMOS RF amplifier, integrated in a 0.18-/spl mu/m CMOS process. The amplifier is implemented on a single chip, requiring no external matching or tuning networks. Peak output power is 27 dBm with a power-added efficiency (PAE) of 34%. The amplitude modulator, implemented on the same chip as the RF amplifier, modulates the supply voltage of the RF amplifier. This results in a power efficient amplification of nonconstant envelope RF signals. The RF power amplifier and amplitude modulator are optimized for the amplification of EDGE signals. The EDGE spectral mask and EVM requirements are met over a wide power range. The maximum EDGE output power is 23.8 dBm and meets the class E3 power requirement of 22 dBm. The corresponding output spectrum at 400 and 600 kHz frequency offset is -59 dB and -70 dB. The EVM has an RMS value of 1.60% and a peak value of 5.87%.     

Power Supply Rejection for RF Amplifiers: Theory and Measurements

Supply noise is a significant problem in RF systems where it can mix with RF signals, degrading signal/noise ratios and potentially causing violation of spectral masks. This paper presents an analysis of the supply rejection properties of RF amplifiers. We extend a conventional Volterra-series formulation to treat multiport systems and use it to describe the mixing products between power supply noise and the RF carrier. It is shown that a multiport Volterra formulation can be used to treat weak nonlinearities in the system and that the nonsymmetric cross terms accurately predict low-order mixing phenomenon. We demonstrate the validity of our hand analysis through the design and fabrication of a power amplifier in 180-nm CMOS, operating between 900 MHz-2.4 GHz with a maximum output power of 15 dBm. Spectral regrowth of single-tone and EDGE modulation waveforms is shown to match within 1-3 dB across frequency and input signal power. Importantly, this analysis provides insight into the circuit-level mechanisms for susceptibility to power supply noise and can help designers improve the power supply rejection ratio robustness of system-on-chip wireless blocks and transmitter architectures.     

High-efficiency power amplifier using dynamic power-supply voltagefor CDMA applications

Efficiency and linearity of the microwave power amplifier are critical elements for mobile communication systems. This paper discusses improvements in system efficiency that are obtainable when a DC-DC converter is used to convert available battery voltage to an optimal supply voltage for the output RF amplifier. A boost DC-DC converter with an operating frequency of 10 MHz is demonstrated using GaAs heterojunction bipolar transistors. Advantages of 10 MHz switching frequency and associated loss mechanisms are described. For modulation formats with a time-varying envelope, such as CDMA, the probability of power usage is described. Gains in power efficiency and battery lifetime are calculated. An envelope detector circuit with a fast feedback loop regulator is discussed. Effects of varying supply voltage with respect to distortion are examined along with methods to increase system linearity     

直接式数字功放技术

音响用的数字功放,普遍由开关电源模块和数字功放模块这两部分组成。非常多的科技人员在研究一个课题:用声频信号调制开关电源模块,开关电源不再输出直流电压,而是直接输出放大的声频信号,进而免去数字功放模块。介绍了一种将开关电源直接设计成数字功放的技术,能简化电路,提高稳定性,能为数字功放带来开关电源软开关技术所具有的优点。     

LINC power amplifier combiner method efficiency optimization

Linear amplification using nonlinear components (LINC) is a method of vector summing two constant amplitude phase-modulated signals to achieve power amplification. The theoretical efficiency of the LINC power amplifier has been reported as 100% since highly efficient nonlinear constant amplitude amplifiers can be used. However, the 100% efficiency performance is only possible at one or two loads along the power output curve. The bulk of the papers regarding LINC has focused on clever implementations of the signal vector decomposition as well as methods to achieve highly linear signal separation. There has been little regard in the literature to the signal combiner implementation necessary to achieve the high power-added efficiency (PAE) of the LINC radio frequency (RF) power amplifier. Efficiency is not an intrinsic property of the combiner implementations, however, the combiner method is the single biggest contributor to efficient performance of a LINC RF power amplifier. This paper develops an analysis method that determines the efficiency of the LINC power amplifier as a function of the amplitude modulation statistics. This can be employed to design the RF communication system amplitude modulation characteristics and to tradeoff and optimize the RF transmitter PAE     

A dual mode charge pump with adaptive output used in a class G audio power amplifier

A dual mode charge pump to produce an adaptive power supply for a class G audio power amplifier is presented.According to the amplitude of the input signals,the charge pump has two level output voltage rails available to save power.It operates both in current mode at high output load and in pulse frequency modulation (PFM) at light load to reduce the power dissipation.Also,dynamic adjustment of the power stage transistor size based on load current at the PFM mode is introduced to reduce the output voltage ripple and prevent the switching frequency from audio range.The prototype is implemented in 0.18μm 3.3 V CMOS technology.Experimental results show that the maximum power efficiency of the charge pump is 79.5%@ 0.5x mode and 83.6%@ lx mode.The output voltage ripple is less than 15 mV while providing 120 mA of the load current at PFM control and less than 18 mV while providing 300 mA of the load current at current mode control.An analytical model for ripple voltage and efficiency calculation of the proposed PFM control demonstrates reasonable agreement with measured results.