米波Ⅲ段宽带功率放大器

利用推挽LDMOS，通过采用传输线变压器宽带匹技术，研制出一种米波Ⅲ段宽带功率放大器。文中给出了测试结果放大器的性能指标良好。     

30MHz-90MHz线性功率放大器的研制

研究和设计射频功率放大器,具有较高的线性度,同时又能实现高功率的稳定输出。着重对射频功率放大器的性能进行分析研究,指出提高功放的线性度的方法;仿真该功率放大器并给出射频功率放大器的硬件电路设计;最后对射频功率放大器进行测试,其性能指标完全达到系统设计要求。     

米波段10W功率放大器的ADS仿真设计

功率放大器是发射机非常关键的部件,广泛应用于通信、雷达等微波系统,其性能将影响整个系统的技术指标,因此微波功率放大器的设计成了微波发射系统的关键。现阶段,米波段雷达的应用越来越广,米波段功率放大器的需求也逐渐增多。介绍利用ADS设计米波段功率放大器的详细过程,并给出量终的实物测试结果,输出功率>10W,增益平坦度<0.5dB,效率>50%,仿真设计结果和实测结果基本一致。     

基于E-PHEMT技术的宽带、高线性和微型封装放大器研究

基于Ga As E-PHEMT工艺,采用负反馈和宽带有耗匹配技术,实现宽带、高线性MMIC放大器芯片;基于多层陶瓷工艺,制作密封性好、可靠性高的封装外壳。结合二者,基于多物理场联合设计、仿真和优化,实现宽带、高线性和小型化功率放大器。该放大器频率覆盖DC~3GHz,增益大于14d B,P-1功率大于23.5d Bm;P-1下PAE大于40%,OIP3大于39dbm,噪声小于3.4d B,输入驻波和输出驻波小于1.5(2GHz)。采用恒流镜像偏置,+5V单电源供电,工作电流小于110m A,封装尺寸仅为4.5mm×2.5mm×1.8mm。可广泛应用于通信等领域。     

非线性功率放大器记忆效应仿真研究

本文在ADS仿真环境下构建了功率放大器的物理模型,用不同间隔的双音频信号仿真的方法定量分析出功率放大器失真产物与输入信号幅度和包络频率之间的关系,验证了功放模型电记忆效应和热记忆效应,仿真结果与理论推导结果一致,并提出了通过优化功放设计来减小记忆效应的方法。     

平衡式E/F类功率放大器的设计与实现

为了解决功率放大器设计过程中存在的效率低和输入/输出端回波损耗较大的问题,设计了一种工作频率为1.5 GHz的平衡式功率放大器。通过采用3 dB定向耦合器对射频信号进行分配及合成,大大降低了输入/输出端的驻波系数,并将逆F类功率放大器的谐波控制网络引入E类功率放大器的匹配电路中。使用ADS对晶体管进行负载牵引和源牵引,得到晶体管的输入/输出阻抗,同时结合晶体管的寄生参数,在输出匹配电路中对二次谐波、三次谐波分别进行开路和短路处理,且为了进一步提高功率放大器的工作性能,在输入电路结构中抑制了二次谐波。选用GaN HEMT器件CGH40010F晶体管,利用ADS软件进行电路仿真,并采用Rogers4350b高频板材制作该功率放大器的实际测试电路板。仿真优化和实测表明：在输入功率为28 dBm时,该功率放大器的输出功率为41.54 dBm,漏极效率为76.99%,功率附加效率（power additional efficiency,PAE）达到73.59%,输入/输出端驻波系数小于2,同时具有160 MHz的高效率带宽,且最大输出功率较单管功率放大器提高了3 dB。实测结果与仿真数据有一定的误差,但仍有较好的一致性,满足设计指标要求,验证了设计方法的可行性。该设计方法具有效率高和回波损耗低的优势,提高了功率放大器的设计效率,使它在当今高效绿色节能的射频微波通信系统中具有广阔的应用前景。     

X波段25W固态功率放大器

介绍X波段25W固态功率放大器单元模块的设计方法和流程,用ADS对微波固态偏置电路进行仿真并且优化,给出仿真结果和最终的设计版图。通过版图制作硬件电路板,测试、调试该放大器电路,最终能够达到预期的设计目标。     

功放与扬声器系统的配接（二）

5.音频功率的传输功率放大器的功率传输,有低阻抗定阻功率传输和高阻抗定压功率传输两种方式。(1)低阻抗定阻功率传输低阻抗定阻功率传输属于功率匹配输出状态,理论上,要求功率放大器的负载阻抗严格等于功率放大器输出级电路负载线的斜率,此时,输出电路处于最佳的设计状态,信号的摆动范围充分利用了功率放大器输出晶体管的线性化区域,功率转换效率最高,即电源利用效率最大,此时,输出功率最大,动态范围最大,失真最小,频响最宽。一个性能优秀的功率放大器,在低阻输出的要求下,放大器能适应一个低阻负载的范围,除能适应标准的8?Ω扬声器系统之…     

一种降低D类功率放大器开关噪声的设计

传统D类功率放大器因特有的开关噪声对水下电子设备的信号接收、通信控制和信号传输等电信号产生很大的干扰,限制了D类功率放大器在水下电子设备中的广泛应用针对这一现象,首先阐明了Σ-Δ调制的D类功率放大器降低开关噪声的原理,然后对传统调制方式和Σ-Δ调制方式的D类功率放大器进行原理分析,并在Simulink软件中进行仿真对比。仿真结果表明,传统D类功率放大器在开关频率处的开关噪声能量高,Σ-Δ调制的D类功率放大器的开关噪声能量分散在一定的带宽内,并且开关噪声能量峰值低于传统D类功率放大器。     

电视发射机中功率放大器的设计

对于电视发射机的研发而言，数字电视发射机的研制重点在于发射机中功率放大器的设计。在明确电视发射机对功率放大器要求的基础上，分析了功率放大器的技术指标及主要组成，并进一步研究了电视发射机功率放大器的设计方案，为我国电视发射系统的发展提供一定的研究价值。     

宽频带换能器电匹配网络设计方法

宽带大功率换能器是现代水声发展的一个重要方向,换能器与功放间的匹配也是其关键技术之一。文中从换能器负载阻抗复角与功放管耗散功率及电源供电效率的关系入手,结合窄带阵元串联或并联调谐方法的特点,确定了适合宽带阵元电匹配网络的电路形式。并针对研制的宽带换能器进行了大功率发射试验,取得了较为满意的结果。     

Merits of PM noise measurement over noise figure: a study at microwave frequencies

This paper primarily addresses the usefulness of phase-modulation (PM) noise measurements versus noise figure (NF) measurements in characterizing the merit of an amplifier. The residual broadband (white PM) noise is used as the basis for estimating the NF of an amplifier. We have observed experimentally that many amplifiers show an increase in the broadband noise of 1 to 5 dB as the signal level through the amplifier increases. This effect is linked to input power through the amplifier's nonlinear intermodulation distortion. Consequently, this effect is reduced as linearity is increased. We further conclude that, although NF is sometimes used as a selection criteria for an amplifier for low-level signal, NF yields no information about potentially important close-to-carrier 1/f noise of an amplifier nor broadband noise in the presence of a high-level signal, but a PM noise measurements does. We also have verified experimentally that the single-sideband PM noise floor of an amplifier due to thermal noise is -177 dBc/Hz, relative to a carrier input power of 0 dBm.     

Wideband linear power amplifier for high-frequency ultrasonic coded excitation imaging

Linear power amplifiers are critical components in ultrasonic imaging systems that implement chirp-coded excitation. Bench-top commercial power amplifiers are usually used in academic laboratories for high-frequency ultrasound imaging, and the imaging performance depends greatly on these general-purpose instruments. To achieve a wide dynamic range, a power amplifier consisting of two stages is developed for chirp-coded ultrasound imaging applications through the implementation of custom-designed broadband 1:1 transformers and the optimization of feedback circuits. The amplifier has broad bandwidth (5 to 135 MHz), maintaining a linearity up to the 1-dB gain compression point (P1dB) of 41.5 dBm, allowing 16 dBm input power level at 60 MHz. The mean and the maximum values of output third-order intercept points (OIP3) are 51.8 and 53.5 dBm, respectively, between 20 and 110 MHz. With 12 dBm input power, the gain of the amplifier varies between 24 and 29 dB, offering a uniformity which would allow excitation of a 70-MHz single-element transducer with windowed chirp-coded bursts sweeping from 40 to 100 MHz. The performance in high-frequency ultrasound imaging is evaluated with a wire phantom. Echo signal-to-noise ratio (eSNR) of the designed amplifier is 7 dB better than a commercial amplifier, and spatial resolution is maintained.     

A microwave photonic generator of chaotic and noise signals

The transition to chaos in a microwave photonic generator has been experimentally studied for the first time, and the generated broadband chaotic microwave signal has been analyzed. The generator represented a ring circuit with the microwave tract containing a low-pass filter and a microwave amplifier. The optical tract comprised a fiber delay line. The possibility of generating chaotic oscillations with uniform spectral power density in a 3–8 GHz range is demonstrated.     

基于改进型匹配网络的宽带高效率E类功放的设计

为了解决E类功放工作带宽过窄的问题,对E类功放的输入、输出匹配网络提出了一种改进方案.该方案中输出匹配网络采用微带线结构与切比雪夫低通匹配网络相结合的方法,在较宽的工作带宽内有效地抑制了谐波;并采用阻抗变换方法设计了含闭式解的宽带带通输入匹配网络,明显增强了输入匹配网络设计的灵活性.利用该方案,同时采用多谐波双向牵引技术得到功率管的最佳源阻抗和负载阻抗,基于CGH40010F功率管设计了一款应用于L波段的宽带高效率E类功放.测试结果表明,在输入功率为28dBm,漏极偏置电压VDS=28V,栅极电压VGS=-3.3V时,在整个L波段频率范围内漏极工作效率大于65%,最高达到83%,输出功率为39~41.1dBm,增益为11~13.1dB,增益平坦度为±1dB.这一结果验证了该改进方案的有效性,使得E类功放具有宽带宽、高效率的性能.     

采用预充开关运放的低功耗12位40MS/s流水线模数转换器

设计了一个采用新型预充快速开启开关运放的低功耗12位40MS/s流水线模数转换器(ADC)。该转换器通过采用新型预充开关运放技术、采样保持电路消去结构、动态比较器和优化采样电容,大大降低了电路的功耗。电路设计采用1.8V 1P6M 0.18μmCMOS工艺,仿真结果表明,在40MS/s采样速率下,输入信号为19MHz时,无杂散动态范围(SFDR)为90.15dB,信噪失真比(SNDR)为72.98dB,功耗为27.9mW。     

Equivalent circuit for broadband underwater transducers

A method is presented to determine the equivalent circuits of broadband transducers with 2 resonances in the frequency band of interest. The circuit parameters are refined by least-squares fitting the measured electrical conductance data with this model. The method is illustrated by computing the conductance and susceptance of the equivalent circuits of 3 types of broadband transducers and comparing them with the measured values. The equivalent circuit of a transducer is necessary for designing filters that match the impedances of the transducer and the power amplifier that drives the transducer.     

Gain improvement in a dual-stage S-band EDFA by filtration of forward C-band ASE

Gain improvement in a dual-stage S-band erbium-doped fiber amplifier (S-band EDFA) is demonstrated using a broadband fiber Bragg grating (FBG) operating in the conventional-band (C-band) region or a C-band/S-band wavelength division multiplexing (WDM) coupler which filters out the forward C-band amplified spontaneous emission (ASE) in the amplifier system, thus increasing the population inversion in the S-band region. The gain for the amplifier with the WDM coupler increases by about 8.5 dB with an input signal power of ?40 dBm, compared to that of the conventional dual-stage amplifier. The gain improvement varies from 4.0–9.2 dB at a wavelength region between 1480 to 1512 nm without a significant noise figure penalty.     

Scaling up of a high average power dye laser amplifier and its new pumping designs

Scaling up of a high average power dye laser amplifier is discussed. Differences in the characteristics between a high average power dye laser amplifier with transverse pumping and longitudinal pumping are presented by a simple theory and simulations. The simulation results for dye laser amplifiers of 10-kW average output power show that longitudinal pumping is as efficient as transverse pumping with the potential of orders of magnitude lower dye flow rate. New pumping designs are also proposed for a dye laser amplifier aimed to achieve high gain with high efficiency to reduce the number of amplifier stages. Simulation results suggest that the new designs, in comparison with a conventional amplifier, can produce several orders of magnitude higher gain without decreasing the conversion efficiency.