Short Millimeter Low Local Wavelength Mixer with Oscillator Power

This paper discusses development, for the 240-GHz region, of whisker contacted diode mixers with LO powers between 10 and 50 µW. Mixer requirements for low parasitic diodes, situated in high-embedding impedance circuits are described and appropriate RF and IF circuit designs presented. A capacitive post RF matching circuit for a full-height waveguide is developed with superior bandwidth characteristics at high impedance levels and greater ease of fabrication than usual matching circuits in reduced height guide. Corroborating experimental results are presented for an X-band model and for a 235-GHz mixer.     

混频器互调失真特性的自动测量

利用计算机控制射频仪器实现对混频器三阶互调失真的自动测量.首先对互调失真测量的基本原理进行了简要介绍,其后论述了利用程序判断测试仪器产生的互调分量对测试结果的影响,并分析了利用频谱分析仪测试互调失真的不确定度.通过对MAX2681下变频混频器的三阶交截点的自动测量,对比芯片资料数据,验证了测试方法在保证测试精度的同时,显著缩短了测试时间.     

Intermodulation Distortion of FDM-FM in Injection-Locked Oscillator

When an injection-locked oscillator is used to amplify a frequency division multiplexing-frequency modulation FDM-FM signal, second- and third-order distortions are found to exist. Explicit expressions are derived that give the signal-to-distortion ratio (NPR) as a function of the locking bandwidth, frequency offset, and various modulation parameters. These formulas are believed to be valid within the limits of the assumptions made.     

Reduction of Mixer Intermodulation by Neutral RF Biasing

The introduction of a neutral RF signal to a nonlinear resistance diode mixer as a means of reducing the effects of undesired intermodulation is described.     

An Analysis of Radio Frequency in Interference Due to Mixer Intermodulation Products

The colocation of high-power communication transmitters and sensitive receivers at a common site frequently causes radio frequency interference due to the generation of spurious intermodulation frequencies in the receiver mixer. These spurious frequencies result from the mixing of the transmitter frequencies with each other and with the receiver local oscillator in the receiver mixer. The problem treated in this paper is that of obtaining an analytical method of predicting the amplitudes of these spurious intermodulation frequencies having been given the amplitude of each of the frequencies at the mixer input.     

A Technique for Determining the Local Oscillator Waveforms in a Microwave Mixer (Short Papers)

A technique is described which enables the large-signal current and voltage waveforms to be determined for a mixer diode. This technique is applicable to any configuration where the impedance seen by the diode at the local oscillator (LO) frequency and its harmonics is known.     

基于混沌理论的无源互调功率预测研究

该文以通信系统中常用的典型微波部件——同轴连接器为研究对象,基于混沌理论对获得的同轴连接器的无源互调(PIM)功率时间序列进行分析,验证了使用混沌理论预测无源互调的有效性。首先通过实验系统获得同轴连接器的3阶无源互调功率时间序列,并对得到的实验数据进行相空间重构,确定该时间序列的最佳嵌入维数m和延迟时间τ。然后,结合最佳嵌入维数和延迟时间,分别构建相图和使用小数据量法计算该时间序列的最大Lyapunov指数,从而从定性和定量角度验证了该无源互调功率时间序列具有混沌特性。在此基础上,基于获得的最大Lyapunov指数对该无源互调功率时间序列进行混沌预测,在最大可预测尺度范围内,理论预测值与实验值最大误差为2.61%,表明采用混沌方法预测无源互调功率效果较好。该文提出的使用混沌理论预测通信系统中微波部件无源互调功率的方法,为开展无源互调抑制技术研究,提高通信系统的性能提供了新思路。

     

Intermodulation Performance of Solid-State UHF Class-C Power Amplifiers

In any frequency-division-multiple-access (FDMA) satellite communication system the control of intermodulation noise must be considered if all signals are amplified by a single nonlinear power amplifier in the satellite transponder. The subject of this paper is the use of Fourier-Bessel series expansion models in the prediction of the intermodulation performance of both traveling-wave-tube (TWT) amplifiers and solid-state class-C UHF amplifiers. Both theoretical and experimental results are described and compared. It is shown that in the case of the solid-state amplifiers a dynamic characteristic measurement technique must be used before reliable predictions can be achieved. A simple intermodulation noise reduction scheme is described for use with high-power efficient class-C solidstate amplifiers. It is demonstrated that a carrier-carrier-to-intermodulation noise power ratio improvement of 10 dB can be achieved with a minimal decrease in prime-power efficiency.     

基于混沌理论的无源互调功率预测研究

该文以通信系统中常用的典型微波部件——同轴连接器为研究对象,基于混沌理论对获得的同轴连接器的无源互调(PIM)功率时间序列进行分析,验证了使用混沌理论预测无源互调的有效性.首先通过实验系统获得同轴连接器的3阶无源互调功率时间序列,并对得到的实验数据进行相空间重构,确定该时间序列的最佳嵌入维数m和延迟时间τ.然后,结合最佳嵌入维数和延迟时间,分别构建相图和使用小数据量法计算该时间序列的最大Lyapunov指数,从而从定性和定量角度验证了该无源互调功率时间序列具有混沌特性.在此基础上,基于获得的最大Lyapunov指数对该无源互调功率时间序列进行混沌预测,在最大可预测尺度范围内,理论预测值与实验值最大误差为2.61％,表明采用混沌方法预测无源互调功率效果较好.该文提出的使用混沌理论预测通信系统中微波部件无源互调功率的方法,为开展无源互调抑制技术研究,提高通信系统的性能提供了新思路.     

Prediction of Gain Expansion and Intermodulation Performance of Nonlinear Amplifiers

A mathematical model for the input‐output characteristic of an amplifier exhibiting gain expansion and weak and strong nonlinearities is presented. The model, basically a Fourier‐series function, can yield closed‐form series expressions for the amplitudes of the output components resulting from multisinusoidal input signals to the amplifier. The special case of an equal‐amplitude two‐tone input signal is considered in detail. The results show that unless the input signal can drive the amplifier into its nonlinear region, no gain expansion or minimum intermodulation performance can be achieved. For sufficiently large input amplitudes that can drive the amplifier into its nonlinear region, gain expansion and minimum intermodulation performance can be achieved. The input amplitudes at which these phenomena are observed are strongly dependent on the amplifier characteristics.     

C波段锁相环式本振源设计

锁相环广泛应用于时钟系统设计,分析了锁相环式本振系统各组成部分的性能及参数.根据锁相倍频原理和环路滤波器传递函数,分析了环路参数的选择,计算了各个参数,并通过实例给出了一种C波段固定频率本振源的系统设计方案,且应用集成芯片成功实现了5.12 GHz固定点频本振源,达到了较为理想的性能.     

微波本振源噪声分析

微波本振源在微波转发设备中是一个关键部件,在现代转发设备中采用大规模单片锁相式频率合成作为本振源,其输出谱线相位噪声直接影响到微波转发设备的输出谱线质量。文中对微波本振源相位噪声进行了描述及对它的几种相位噪声特点进行了分析,并得出微波本振源环路总相位噪声功率谱密度表达式以及锁相环的环路带宽选择原则。     

Design Techniques and Intermodulation Analysis of Broad-Band Solid-State Power Amplifiers

This paper presents balanced circuit techniques for the reduction and cancellation of the dominating third-order intermodulation tion product generated by broad-band solid-state power amplifiers. These techniques are applicable to collocated transmitters where the interference enters through the output port of the transmitter. A rigorous derivation is presented to prove the validity of the intermodulation canceliation by using a quadrature-hybrid coupling scheme in a balanced circuit configuration. The results are valid for arbitrary nonlinear characteristics exhibited by general classes of amplifiers, as well as isolators.     

Analysis and Improvement of Intermodulation Distortion in GaAs Power FET's

Tailoring of the doping profile is a powerful tool in reducing the intermodulation distortion (IMD) in GaAs power FET's. Reproducible and uniform preparation of the required profiles is a difficult task for epitaxial techniques. This shortcoming has motivated the present investigation of fabricating highly linear power FET's by ion implantation. An analytical divice model was developed for exploring the relationship between the active layer profile and the IMD. These calculations revealed a complex behavior in the variation of the distortion levels due to partial correlation between the contributions arising from nonlinear transconductance and output conductance. The device model was used to identify implant doses and energies for approaching an optimum active layer profile. Based on the results, a deep Se implant followed by a shallow compensating Be implant to reduce the doping level close to the surface was used in the device fabrication. The IMD of the transistors was measured by the two-tone method. Conventional epitaxial FET's with a flat doping profile were evaluated for comparison purposes. This comparison demonstrated that a 4-dB increase in the intercept point for the third-order intermodulation product can be realized by using the tailored implanted profile. The experiments demonstrated that the tuning conditions for maximum output power and minimum IMD are virtually identical for the implanted transistors, in contrast to the behavior of conventional devices with flat doping profiles. These performance advantages, coupled with the high levels of uniformity and reproducibility of doping parameters, show ion implantation to be a powerful technique in the fabrication of highly linear power FET's.     

基于注频锁相技术的接收天线本振阵列

文中以注频锁相技术为基础,提出一维和二维注频锁相耦合本振阵列基本结构,分析了注频锁相本振阵列的相位动力学方程,推导了稳定同步状态本振信号间的相对相移与振荡器自由振荡频率的关系,为注频锁相技术在接收天线本振阵列的应用提供理论基础.     

高功率单频主振荡光纤功率放大器研究进展

高功率单频主振荡光纤功率放大器在相干合束、引力波传感器、自由空间光通信、测距、激光雷达、非线性频率转换等有广泛应用。综述了高功率单频主振荡光纤功率放大器的国内外研究进展,分析了高功率单频光纤放大器关键技术,如种子激光源、受激布里渊散射与放大自发辐射噪声的抑制技术,指出了千瓦量级的主振荡光纤功率放大器未来的研究方向。     

一种适用于超低功耗MCU的振荡器设计

提出并设计了一种新型低速振荡器,利用MCU电路内部的主时钟对低速时钟进行测试并且自校准,在几乎不增加功耗的前提下可以大大提高低速振荡器的精度和稳定性。与常规的低速振荡器相比,该结构具有功耗低、精度高、稳定性好的优点。仿真结果表明,此电路结构符合设计预期。     

一种超低功耗RC振荡器设计

基于SMIC 55 nm CMOS工艺,设计并制备了工作在1.2V电源电压下的超低功耗RC振荡器.该振荡器主要包括运算放大器、压控振荡器(VCO)、基准电流源、低温漂电阻和可修调开关电容以及非交叠时钟产生电路.该振荡器用工作在亚阈值区的运算放大器和VCO取代了传统单比较器型RC振荡器中的比较器,显著降低了功耗;用开关电容取代了充放电电容,并且将输出时钟的频率转换成了阻抗,与参考电阻进行比较.利用负反馈环路锁定了输出时钟信号频率,从而得到了稳定的时钟信号.测试结果表明,1.2V电源电压、27℃环境下,该RC振荡器的输出时钟信号频率为32.63 kHz,功耗为65 nW;在-10 ～ 100℃,其温度系数为1.95×10-4/℃;在0.7～1.8 V电源电压内,其电源电压调整率为3.2％/V.芯片面积为0.168 mm2.     

Coaxial Cables as Sources of Intermodulation Interference at Microwave Frequencies

Intermodulation interference arising from nonlinearities in braided coaxial cables at microwave frequencies is discussed. Detailed investigations have been carried out using a large number of commercially available and specially constructed cables to isolate and assess the relative contributions of different parameters of coaxial cables responsible for the generation of intermodulation products (IP's) at L-, S-, and C-band frequencies centered on 1.5, 3, and 5 GHz. Ambient temperature in the case of polythene dielectric cables and oxides on copper-wire braids affect considerably the IP's generated in a coaxial cable.